Question

please solve the answer correctly....
maths question class 8 algebraic expressions and identities​

Answer 1

Answer:

1. (2r-1)(2r+1)(4r²+1)

=((2r²)-1²)(4r²+1)

=(4r²-1)(4r²+1)

=((4r²)-1²)

=16r⁴-1

2. 2x+1/3x =5

squaring on both side

=(2x)²+(1/3x²)=5²

=4x²+1/9x²=25

3. (x+1/x)(x-1/x)

=(x)²-(1/x)²

=x²-1/x²

=x⁴-1/x²

4. (7.95)² - (2.05)²/(7.95-2.05)

=(7.95-2.05)(7.95+2.05)/(7.95-2.05)

=(7.95+2.05)

5. x²y²-(-3x²y²)

=x²y²+3x²y²

=4x²y²

6. (a+b)²-(a-b)²

=(a+b(a-b))(a+b-(a-b))

=(a+b+a-b)(a+b-a+b)

=2a×2b

7. coefficient of y = -1/3

8. (3x-4y)²

=(3x)²+(4y)²-2×3x×4y

=9x²+16y²-24xy

9. 8x=(45)²-(43)²

8x=2025-1848

8x=176

x=176/8

x=22

10. (l/m - m/l)²

(l/m)²+(m/l)²-2×l/m×m/l

l²/m²+m²/l²-2