Question
Show that:
$ (3 x+7)^2-84 x=(3 x-7)^2 $
$ (3 x+7)^2-84 x=(3 x-7)^2 $
✓
Answer
To simplify, we will proceed as follows:
$ (3 x+7)^2-84 x=(3 x-7)^2 $
$ \text { LHS }=(3 x+7)^2-84 x $
$ =(3 x+7)^2-4 \times 3 x \times 7 $
$ =(3 x-7)^2\left[\because(a+b)(a-b)=a^2-b^2\right] $
$= RHS$
Because $LHS$ is equal to $RHS,$ the given equation is verified.
$ (3 x+7)^2-84 x=(3 x-7)^2 $
$ \text { LHS }=(3 x+7)^2-84 x $
$ =(3 x+7)^2-4 \times 3 x \times 7 $
$ =(3 x-7)^2\left[\because(a+b)(a-b)=a^2-b^2\right] $
$= RHS$
Because $LHS$ is equal to $RHS,$ the given equation is verified.
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