 # Algebraic Expressions and Identities:NCERT Solutions for Class 8 Maths Chapter 9 Exercise 9.3

In this page we have Algebraic Expressions and Identities:NCERT Solutions for Class 8 Maths Chapter 9 for Exercise 9.3 . Hope you like them and do not forget to like , social share and comment at the end of the page.
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:
1. 4p(q + r) =  4pq + 4pr
2. ab(a - b) = a2b - ab2
3. (a + b) (7a2b2) = 7a3b2 + 7a2b3
4. (a2 - 9)(4a) = 4a3 - 36a2
5. (pq + qr + rp) x 0 = 0
Question 2
Find the product.
i) a2 x (2a22) x (4a26)
ii) (2xy/3) ×(-9x2y2/10)
(iii)    (-10pq3/3) ×(6p3q/5)
(iv)    ( x) x (x2) x (x3) x (x8)
Answer: We will use the below property extensively in above questions
am x an x ao = am+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 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
1+ 1+ 1 = 1 + 1 + 1 = 3
(iii) Putting a = -1 in the equation we get
-13+1-1 = -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: i) (p2 - pq) + (q2 - qr) + (r2 - pr)
= p2 + q2 + r2 - pq - qr - pr
ii) (2xz - 2x2 - 2xy) + (2yz - 2y2 - 2xy)
= 2xz - 4xy + 2yz - 2x2 - 2y2
iii) (40ln - 12lm + 8l2) - (3l2 - 12lm + 15ln)
= 40ln - 12lm + 8l2 - 3l2 - 12lm + 15ln
= 55ln - 24lm + 5l2
iv) = (-4ac + 4bc + 4c2) - (3a2 + 3ab + 3ac)
= -4ac + 4bc + 4c2 - 3a2 - 3ab - 3ac
= -7ac + 4bc + 4c2 - 3a2 - 3ab

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Reference Books for class 8 Math

Given below are the links of some of the reference books for class 8 Math.

1. Mathematics Foundation Course for JEE/Olympiad : Class 8 This book can take students maths skills further. Only buy if child is interested in Olympiad/JEE foundation courses.
2. Mathematics for Class 8 by R S Aggarwal Detailed Mathematics book to clear basics and concepts. I would say it is a must have book for class 8 student.
3. Pearson Foundation Series (IIT -JEE / NEET) Physics, Chemistry, Maths & Biology for Class 8 (Main Books) | PCMB Combo : These set of books could help your child if he aims to get extra knowledge of science and maths. These would be helpful if child wants to prepare for competitive exams like JEE/NEET. Only buy if you can provide help to the child while studying.
4. Reasoning Olympiad Workbook - Class 8 :- Reasoning helps sharpen the mind of child. I would recommend students practicing reasoning even though they are not appearing for Olympiad.

You can use above books for extra knowledge and practicing different questions.

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