Question

а) (1+5х)(5х-1)=10х-1;
б)(2х+7)(7-2х)=49+7х.

Answer 1

a)(1+5х)(5х-1)=10х-1
5x-1+25x²-5x=10x-1
25x²-1=10x-1
25x²-10=0
25²=10
x²=0.4
x=+-√0.4
б)(2х+7)(7-2х)=49+7х
14x-4x²+49-14x=49+7x
49-4x²=49+7x
-4x²=7x
-4x²-7x=0
-x(4x+7)=0
4x+7=0        x=-7/4
-x=0             x=0