NCERT Solutions for Class 8 Mathematics Chapter 9
Important NCERT Questions
Algebraic Expressions and Identities Chapter 9 Exercise 9.5
NCERT Books for Session 2022-2023
CBSE Board
Questions No: 5
Show that: (i) (3x+7) ² -84x=(3x-7) ² (ii) (9p-5q) ² + 180pq =(9p+5q) ²
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(i) L.H.S= (3x+7)²-84x=(3x)²+2x3xX7+(7)²-84x
[Using identity (a+b)²=a²+2ab+b²]
= 9x²+42x+49-84x
= 9x²-42x+49
= (3x-7)² [∵ (a-b)²=a²+2ab+b²]
= R.H.S.
(ii) LHS = (9p-5q)²+180pq=(9p)²-2x9px5q+(5q)²+180pq
[Using identity (a-b)²=a²-2ab+b²]
= 81p²-90pq+25q²+180pq
= 81p²+90pq²+25q²
= (9p+5q)² [∵ (a-b)²=a²-2ab+b²]
Class 8 Maths Chapter 9 Exercise 9.5 Solution in Video
for more answers vist to:
https://www.tiwariacademy.com/ncert-solutions/class-8/maths/chapter-9/