NCTB Class 6 Math Chapter Four Exercise 4.2 Solution by Math Expert. Bangladesh Board Class 6 Math Solution Chapter 4 “Algebraic Expressions’’ Exercise 4.2 Solution.
Board |
NCTB |
Class |
6 |
Subject |
Mathematics |
Chapter |
4 |
Chapter Name |
“Algebraic Expressions’’ |
Exercise |
4.2 Solution |
Exercise:- 4.2
(1) Simplify:
Solution:-
(i) x3 X x7
= x10
(ii) a3 x a x a5
= a9
(iii) x4 X x2X x9
=x15
(iv) m x m2 x n3 x m3 x n7
=m6 n10
(v) 3a x 4b x2a x 5c x3b
= 360 a2 b2 c
(vi) 2x2 X y2 X 2z2 X 3y2 X 4x2
= 48 x4 y4 z2
(2) If a=2, b=3, c=1, find the value of each of the following expressions:
Solution:-
(i) a3 + b2
= (2)2+ (3)2
= 8+27
= 35 [Therefore a=2; b=3]
(ii) b + c
= 27+1
= 28
(iii) a2–b2 +c2
= (2)2 – (3)2 + (1)2
= 4-9+1
= -5+1
= -4
(iv) b2– 2ab+a2
= (3)2 – 2X2X3+ (2)2
= 9-12+4
= -3+4
= 1
(v) a2 -2ac+c2
= (2)2 – 2X2X1+12
= 4-4+1
= 1
(3) If x=3, y=5, z=2, show that
Solution:-
Therefore, L.H.S, y2-x2
= (y+x) (y-x)
= (5+3) (5-3)
= 8×2
= 16
R.H.S, (x+y) (y-x)
= (3+5) (5-3)
= 8×2
= 16
Therefore, L.H.S= R.H.S (proved)
(ii) L.H.S, (x+y)2
= x 2+ 2xy+y2
= (3)2 + 2x3x5 +52
= 9+30+25
= 64
R.H.S, (x-y) + 4xy
= (x+y)2
= (3+5)2
= (8)2
= 64
Therefore, L.H.S = R.H.S (proved)
(iii) L.H.S, (y+z)2
= (5+2)2
= (7)2
= 49
R.H.S, y+2xz+z
= 52 +2x5x2+22
= 25+20+4
= 49
Therefore, L.H.S= R.H.S (proved)
(iv) L.H.S, (x+z)2
= (3+2)2
= (5)2
= 25
R.H.S, x+2xz+z
= 32+2x3x2+22
= 9+12+4
= 25
Therefore, L.H.S= R.H.S (proved)
(4) Tick the correct answer:
Solution:-
(i) a7x a8
= a15 (b)
(ii) a3 x a-3
= a0(c)
(iii) 5x2 X 4x4
= 20x6 (b)
(iv) x5X x4
= x9
(v) 5a3X a5
= 5a8
Some questions and answers are not matched with the guide.