Question

(3x + 7)²-84x= (3x - 7)²​

Answer 1

Step-by-step explanation:

9x2+49+21x-84x=9x2+49-21x

-63x=-21x

-63x+21x=0

-42x=0

x=0

I hope it may help you

Answer 2

☆ (3x + 7)² - 84x = (3x - 7)²

➥ (3x)² + 2 × 3x × 7 + (7)² - 84x

➥ 9x² + 42x + 49 - 84x

➥ 9x² - 42x + 49 = (3x - 7)²

➥ R.H.S.

☆ Hence proved.