NCERT Solutions For Class 8 Maths Chapter 9,Algebraic Expressions And Identities, Exercise 9.3

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Class 8, Maths, Chapter 9, Exercise 9.3, Solutions

Q.1. Carry out the multiplication of the expressions in each of the following pairs.

(i) 4p,q + r

(ii) ab,a – b

(iii) a+b,7a²b²

(iv) a² – 9,4a

(v) pq + qr + rp,0

Ans:

(i) 4p,q + r

⇒ 4p × (q+ r)

⇒ (4p × q) + (4p×r)

⇒ 4pq + 4pr (Ans.)

(ii) ab,a – b

⇒ ab (a –b)

⇒ (ab×a)-(ab×b)

⇒ a²b – ab² (Ans.)

(iii) a+b, 7a²b²

⇒ (a + b) × 7a²b²

⇒ (a ×7a²b²) + (b ×7a²b²)

⇒ 7a³b² + 7a²b³ (Ans.)

(iv) a² – 9,4a

⇒ (a² – 9) × 4a

⇒ (a² × 4a) – (9 × 4a)

⇒ 4a³ – 36a (Ans.)

(v) pq + qr + rp,0

⇒ (pq + qr + rp) × 0

= 0 (Ans.)

Q.2. Complete the table.

Q.3. Find the product.

(i) (a²)×(2a²²)×(4a²⁶)

(ii) $\left( \frac{2}{3}xy \right)\times \left( \frac{-9}{10}{{x}^{2}}{{y}^{2}} \right)$

(iii) $\left( -\frac{10}{3}p{{q}^{3}} \right)\times \left( \frac{6}{5}{{p}^{3}}q \right)$

(iv) x×x² × x³ × x⁴

Q.4. (a) Simplify 3x(4x–5)+3 and find its values for (i) x=3 (ii) x= $\frac{1}{2}$

(b) Simplify a(a²+a+1)+5 and find its value for (i) a=0, (ii) a=1 (iii) a= –1

Q.5. (a) Add: p(p–q),q(q–r) and r(r–p)

(b) Add: 2x(z–x–y) and 2y (z–y–x)

(c) Subtract: 3l(l – 4 m+5n) from 4l(10n –3 m+2l)

(d) Subtract: 3a(a+b+ c) –2b(a–b+c) from 4c(–a+b+c)