Question

(2х-5)*(2х+5)-4х в квадрате помогите

Answer 1

$(2x-5)(2x+5)-4x^2=4x^2-25-4x^2=-25$

$(a-b)(a+b)=a^2-b^2$

Answer 2

$(2x-5)(2x+5)-4 x^{2} =(2x)^2-5^2-4 x^{2} =4 x^{2} -25-4 x^{2} =-25$