Question

Calculati : a) (x+4)² + (x-2)² -2x² b) (2x-3) -(3x+5) +(2x+5)(2x-5)

Answer 1

$a).(x+4)^2+(x-2)^2-2x^2= \\ =x^2+2 \cdot x \cdot 4+4^2+x^2-2 \cdot x \cdot 2+2^2-2x^2= \\ =x^2+8x+16+x^2-4x+4-2x^2=4x+20$
$b). (2x-3) -(3x+5) +(2x+5)(2x-5)= \\ =2x-3-3x-5+4x^2-25=4x^2-x-33$