Question

(x+10)^2=(x-9)^2 решение

Answer 1

Формула a^2 - b^2 = (a - b)(a + b)

(x + 10)^2 - (x -9)^2 = 0 
(x + 10 + x - 9) (x + 10 - x + 9) = 0
(2x + 1) *19 = 0 
2x = - 1 
x = - 1/2 = - 0,5 

Answer 2

спасибо

Answer 3

x^2+20x+100=x^2-18x+81
x^2-x^2+20x+18x=81-100
38x=-19
x=-19/38
x=-0,5