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Exercise 9.1 - Chapter 9 Algebraic Expressions & Identities class 8 ncert solutions Maths - SaraNextGen [2024-2025]


Question 1:

Identify the terms, their coefficients for each of the following expressions.

(i) 5xyz2 − 3zy

(ii) 1 + x + x2

(iii) 4x2y2 − 4x2y2z2 + z2

(iv) 3 − pq + qr − rp

(v)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2234/Exercise%209_html_m160c4154.gif

(vi) 0.3a − 0.6ab + 0.5b

Answer:

The terms and the respective coefficients of the given expressions are as follows.

Terms

Coefficients

(i)

5xyz2

− 3zy

5

− 3

(ii)

1

x

x2

1

1

1

(iii)

4x2y2

− 4x2y2z2

z2

4

− 4

1

(iv)

3

− pq

qr

− rp

3

−1

1

−1

(v)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2234/Exercise%209_html_319911b4.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2234/Exercise%209_html_m51940abb.gif

− xy

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2234/Exercise%209_html_m5a4d85ce.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2234/Exercise%209_html_m5a4d85ce.gif

− 1

(vi)

0.3a

− 0.6ab

0.5b

0.3

− 0.6

0.5

Question 2:

Classify the following polynomials as monomials, binomials, trinomials. Which polynomials do not fit in any of these three categories?

x + y, 1000, x + x2 + x3 + x4, 7 + y + 5x, 2y − 3y2, 2y − 3y2 + 4y3, 5x − 4y + 3xy, 4z − 15z2ab + bc + cd + dapqrp2q + pq2, 2p + 2q

Answer:

The given expressions are classified as

Monomials: 1000, pqr

Binomials: x + y, 2y − 3y2, 4z − 15z2p2q + pq2, 2p + 2q

Trinomials: 7 + y + 5x, 2y − 3y2 + 4y3, 5x − 4y + 3xy

Polynomials that do not fit in any of these categories are

x + x2 + x3 + x4ab + bc + cd + da

Question 3:

Add the following.

(i) ab − bcbc − caca − ab

(ii) a − b + abb − c + bcc − a + ac

(iii) 2p2q2 − 3pq + 4, 5 + 7pq − 3p2q2

(iv) l2 + m2m2 + n2n2 + l2, 2lm + 2mn + 2nl

Answer:

The given expressions written in separate rows, with like terms one below the other and then the addition of these expressions are as follows.

(i)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2238/Chapter%209_html_m5965c9af.gif

Thus, the sum of the given expressions is 0.

(ii)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2238/Chapter%209_html_b18dce0.gif

Thus, the sum of the given expressions is ab + bc + ac.

(iii)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2238/Chapter%209_html_72ec14d0.gif

Thus, the sum of the given expressions is −p2q2 + 4pq + 9.

(iv)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2238/Chapter%209_html_7b3878cd.gif

Thus, the sum of the given expressions is 2(l2 + mnlm + mn + nl).

Question 4:

(a) Subtract 4a − 7ab + 3b + 12 from 12a − 9ab + 5b − 3

(b) Subtract 3xy + 5yz − 7zx from 5xy − 2yz − 2zx + 10xyz

(c) Subtract 4p2q − 3pq + 5pq2 − 8p + 7q − 10 from 18 − 3p − 11q + 5pq − 2pq2 + 5p2q

Answer:

The given expressions in separate rows, with like terms one below the other and then the subtraction of these expressions is as follows.

(a)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2240/Chapter%209_html_m3163e6df.gif

(b)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2240/Chapter%209_html_7928b0c.gif

(c)

https://img-nm.mnimgs.com/img/study_content/curr/1/8/5/72/2240/Chapter%209_html_m7c843b8e.gif

Also Read : Exercise-9.2-Chapter-9-Algebraic-Expressions-&-Identities-class-8-ncert-solutions-Maths

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