Question

What is the factor form of 2x^2-25=0 and -4x^2+81=0

Answer 1

$2x^2-25=0\\\\(x\sqrt2)^2=5^2=0\\\\(x\sqrt2-5)(x\sqrt2+5)=0\\-------------------------\\-4x^2+81=0\\\\81-4x^2=0\\\\9^2-(2x)^2=0\\\\(9-2x)(9+2x)=0\\------------------------\\Used:\\(a-b)(a+b)=a^2-b^2$