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Class 8 Maths Exercise 8.3 Solutions : Algebraic Expressions and Identities

In this page we have Class 8 Maths Exercise 8.3 Solutions for Algebraic Expressions and Identities. This exercise has questions about multiplication of polynomials like mononial to binomial and mononial to Trinomial. Hope you like them and do not forget to like , social share and comment at the end of the page.

Class 8 Maths Exercise 8.3 Solutions

Question 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
Answer:

4p(q + r) = 4pq + 4pr
ab(a - b) = a²b - ab²
(a + b) (7a²b²) = 7a³b² + 7a²b³
(a² - 9)(4a) = 4a³ - 36a²
(pq + qr + rp) x 0 = 0

Question 2
Complete the table. Class 8 Maths Exercise 8.3 Solutions

Answer:
(i) a(b + c + d) = ab + ac + ad

(ii) (x + y – 5) 5xy= 5x²y + 5xy² -25xy
(iii)p(6p²– 7p + 5)=6p³ -7p² +5p
(iv) 4p²q²(p² - q²)=4p⁴q² -4p²q⁴
(v) (a + b + c)abc= a²bc + ab²c + abc²

Question 2
Find the product.
(i) a² x (2a²²) x (4a²⁶)
(ii) (2xy/3) ×(-9x²y²/10)
(iii) (-10pq³/3) ×(6p³q/5)
(iv) x (x²) x (x³) x (x⁸)
Answer: We will use the below property extensively in above questions
a^m x aⁿ x a^o = a^m+n+o
(i) As you know
So, we get
a² x (2a²²) x (4a²⁶) = 8a⁴⁸
(ii) (2xy/3) ×(-9x²y²/10)
=(-3x³y³/5)
(iii) (-10pq³/3) ×(6p³q/5)
=(-4p⁴q⁴)
(iv)( x) x (x²) x (x³) x (x⁸)
= x¹⁴

Question 3
(a) Simplify 3x (4x - 5) + 3 and find its values for (i) x = 3 (ii) x =1/2
(b) Simplify a (a²+ a + 1) + 5 and find its value for (i) a = 0, (ii) a = 1 (iii) a = - 1.
Answer
(a)
(i) Putting x=3 in the equation we get
12x² - 15x + 3 =108-45+3 = 66
(ii) putting x=1/2 in the equation we get
$12 \times \frac {1}{2} - \frac {15}{2} + 3 =3 - \frac {15}{2} -3=\frac {-3}{2}$
(b)
a(a²a+1)
=a³+a²+a
(i) putting a= 0 in the equation we get
0³+0²+0=0
(ii) putting a=1 in the equation we get
1³+ 1²+ 1 = 1 + 1 + 1 = 3
(iii) Putting a = -1 in the equation we get
-1³+1²-1 = -1 + 1 + 1 = 1

Question 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 + 5 n) from 4l ( 10 n - 3 m + 2 l )
(d) Subtract: 3a (a + b + c ) - 2 b (a - b + c) from 4c ( - a + b + c )
Answer: (a) (p² - pq) + (q² - qr) + (r² - pr)
= p² + q² + r² - pq - qr - pr
(b) (2xz - 2x² - 2xy) + (2yz - 2y² - 2xy)
= 2xz - 4xy + 2yz - 2x² - 2y²
(c) (40ln - 12lm + 8l²) - (3l² - 12lm + 15ln)
= 40ln - 12lm + 8l² - 3l² - 12lm + 15ln
= 55ln - 24lm + 5l²
(d) = (-4ac + 4bc + 4c²) - (3a² + 3ab + 3ac)
= -4ac + 4bc + 4c² - 3a² - 3ab - 3ac
= -7ac + 4bc + 4c² - 3a² - 3ab

Summary

Class 8 Maths Exercise 8.3 Solutions has been prepared by Expert with utmost care. If you find any mistake.Please do provide feedback on mail. You can download the solutions as PDF in the below Link also
Download Class 8 Maths Exercise 8.3 as pdf
This chapter 8 has total 4 Exercise 8.1 ,8.2 ,8.3 ,8.4 as per latest syllabus. Exercise 8.5 is deleted as per latest syllabus. This is the Third exercise in the chapter.You can explore previous exercise of this chapter by clicking the link below

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