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Miscellaneous Exercise - Chapter 5 Continuity & Differentiability class 12 ncert solutions Maths - SaraNextGen [2024]


Question 1:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7014/Chapter%205_html_d961562.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7014/Chapter%205_html_m4d94c2f0.gif

Using chain rule, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7014/Chapter%205_html_m3c95ac0f.gif

Question 2:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7015/Chapter%205_html_m3549a5f.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7015/Chapter%205_html_6b8a7ae0.gif

Question 3:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7016/Chapter%205_html_5c8f433.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7016/Chapter%205_html_m4e5ec0bf.gif

Taking logarithm on both the sides, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7016/Chapter%205_html_2f8798fc.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7016/Chapter%205_html_m76406458.gif

Question 4:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7017/Chapter%205_html_m51f28dd5.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7017/Chapter%205_html_m656ffe8.gif

Using chain rule, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7017/Chapter%205_html_m5eefc5ae.gif

Question 5:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7018/Chapter%205_html_2aa0355a.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7018/Chapter%205_html_m12f45499.gif

Question 6:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7019/Chapter%205_html_m6052363f.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7019/Chapter%205_html_m3ee6a316.gif

Therefore, equation (1) becomes

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7019/Chapter%205_html_17aff96e.gif

Question 7:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7020/Chapter%205_html_m4826e034.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7020/Chapter%205_html_m297fcb9d.gif

Taking logarithm on both the sides, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7020/Chapter%205_html_m7b8e6006.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7020/Chapter%205_html_m33b8f35d.gif

Question 8:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7021/Chapter%205_html_5b73740e.gif for some constant a and b.

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7021/Chapter%205_html_m76132c97.gif

By using chain rule, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7021/Chapter%205_html_454748c.gif

Question 9:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7022/Chapter%205_html_m1fa12acd.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7022/Chapter%205_html_m640ad7d0.gif

Taking logarithm on both the sides, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7022/Chapter%205_html_m7c35ee16.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7022/Chapter%205_html_1ad53114.gif

Question 10:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_2e33058e.gif , for some fixed https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_2b84d6e8.gif and https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_m4b6c9f17.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_1b6ce38c.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_m4e23c929.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_m2b571ec3.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_22731031.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_m29814724.gif

s = aa

Since a is constant, aa is also a constant.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_m28f31a96.gif

From (1), (2), (3), (4), and (5), we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7025/Chapter%205_html_m32f7549d.gif

Question 11:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_m17e50c14.gif , for https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_5f6ad269.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_31a56b1e.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_3c96230d.gif

Differentiating with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_4c578ae1.gif

Also,

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_7d588169.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_1f5c0947.gif

Substituting the expressions of https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_5c6433d9.gif in equation (1), we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7029/Chapter%205_html_a5b5dce.gif

Question 12:

Findhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7033/Chapter%205_html_m72221781.gif , if https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7033/Chapter%205_html_m4f34563e.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7033/Chapter%205_html_6ee472a6.gif

Question 13:

Findhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7037/Chapter%205_html_m72221781.gif , if https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7037/Chapter%205_html_mce3ef6b.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7037/Chapter%205_html_4ecf365e.gif

Question 14:

Ifhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7060/Chapter%205_html_3daa2805.gif , for, −1 < x <1, prove that

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7060/Chapter%205_html_m224d4bdb.gif

Answer:

It is given that,

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7060/Chapter%205_html_3daa2805.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7060/Chapter%205_html_426367e2.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7060/Chapter%205_html_m32da6f71.gif

Hence, proved.

Question 15:

Ifhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7062/Chapter%205_html_m7e6932d6.gif , for some https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7062/Chapter%205_html_m1d5b5d3a.gif  prove that

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7062/Chapter%205_html_37a69f32.gif  is a constant independent of a and b.

Answer:

It is given that,https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7062/Chapter%205_html_m7e6932d6.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7062/Chapter%205_html_m2884619c.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7062/Chapter%205_html_m6c362b98.gif

Hence, proved.

Question 16:

If https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7065/Chapter%205_html_m40bdcc27.gif  with https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7065/Chapter%205_html_2a028ca2.gif  prove thathttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7065/Chapter%205_html_me8599ba.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7065/Chapter%205_html_m44367968.gif

Then, equation (1) reduces to https://img-nm.mnimgs.com/img/study_content/content_ck_images/images/Selection_014(11).png

⇒sina+y-ydydx=cos2a+y⇒dydx=cos2a+ysina

Hence, proved.

Question 17:

If https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7067/Chapter%205_html_8f1f0cd.gif andhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7067/Chapter%205_html_53d730be.gif , find https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7067/Chapter%205_html_77854302.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7067/Chapter%205_html_2d91050f.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7067/Chapter%205_html_mbbd3588.gif

Question 18:

Ifhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_m36a0c721.gif , show that https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_6fa7e8e0.gif exists for all real x, and find it.

Answer:

It is known that, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_m4f621101.gif

Therefore, when x ≥ 0, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_m111c14a3.gif

In this case, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_mfaad15d.gif  and hence, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_5084904b.gif

When x < 0, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_m59a92318.gif

In this case, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_m27db3809.gif  and hence, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_md75c8fa.gif

Thus, forhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_m36a0c721.gifhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_6fa7e8e0.gif exists for all real x and is given by,

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7070/Chapter%205_html_534c3f5e.gif

Question 19:

Using mathematical induction prove that https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7072/Chapter%205_html_m5e5f6281.gif for all positive integers n.

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7072/Chapter%205_html_m265b040e.gif

For n = 1,

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7072/Chapter%205_html_m2a97324c.gif

∴P(n) is true for n = 1

Let P(k) is true for some positive integer k.

That is, https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7072/Chapter%205_html_19a5767d.gif

It has to be proved that P(k + 1) is also true.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7072/Chapter%205_html_m364fa7b2.gif

Thus, P(k + 1) is true whenever P (k) is true.

Therefore, by the principle of mathematical induction, the statement P(n) is true for every positive integer n.

Hence, proved.

Question 20:

Using the fact that sin (A + B) = sin A cos B + cos A sin B and the differentiation, obtain the sum formula for cosines.

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7073/Chapter%205_html_16c8c39e.gif

Differentiating both sides with respect to x, we obtain

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7073/Chapter%205_html_3406b25.gif

Question 21:

Does there exist a function which is continuos everywhere but not differentiable at exactly two points? Justify your Answer ?

Answer:

y=x           -∞  It can be seen from the above graph that, the given function is continuos everywhere but not differentiable at exactly two points which are 0 and 1.

Question 22:

Ifhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7074/Chapter%205_html_224f5d17.gif , prove that https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7074/Chapter%205_html_5c68ffc9.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7074/Chapter%205_html_m25dad79b.gif

Thus,

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7074/Chapter%205_html_5c68ffc9.gif

Question 23:

Ifhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7077/Chapter%205_html_7ecf9df6.gif , show that https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7077/Chapter%205_html_m1b5f0ead.gif

Answer:

It is given that,https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7077/Chapter%205_html_m4436e0e4.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7077/Chapter%205_html_m613dfb4.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/12/15/234/7077/Chapter%205_html_m41b41031.gif

Also Read : Exercise-6.1-Chapter-6-Applications-Of-Derivatives-class-12-ncert-solutions-Maths

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