Question

(2х-5)^2-4х^2-20х,якщох=0,25

Answer 1

(2x - 5)^2 - 4x^2 - 20x =

(2x)^2 - 2 · 2x · 5 + 5^2 - 4x^2 - 20x =

4x^2 - 20x + 25 - 4x^2 - 20x =

= - 40x + 25 ;

если x = 0,25 , то - 40x + 25 =

= - 40 · 0,25 + 25 = - 10 + 25 = 15 .