Question

show that
$(3x + 7) ^{2} - 84x = (3x - 7) ^{2}$
​

Answer 1

Step-by-step explanation:

LHS =(3x+7)

2

−84x

Using , (a+b)

2

=a

2

+2ab+b

2

=(9x

2

+42x+49)−84x

=9x

2

−42x+49

Using , (a−b)

2

=a

2

−2ab+b

2

=(3x)

2

−2(3x)(7)+(7)

2

=(3x−7)

2

= RHS