Question

(4x-3)² = (4x+7)² =?

Answer 1

$(4x-3)^2= (4x)^2 - 2 * 4x * 3+ 3^2 \longrightarrow16x^2-24x+9 \\\\\\ (4x+7)^2=(4x)^2 + 2*4x*7+7^2 \longrightarrow16x^2+56x+49$

Answer 2

(4x)^2-2×4x×3+3^2=
(4x)^2+2×4x×7+7^2
16x^2-24x+7=
16x^2+56x+49
-24x+7=56x+49
7-49=56x+24x
-42=80x
x= -42/80= -21/40