3(x^2 - 8x + 16) - 3x^2 =
= 3x^2 - 24x + 48 - 3x^2 =
= - 24x + 48
Х^2-26х+169=-52х
х^2+26х+169=0
Д=676-676=0
х=-26/2=-13
A) (x+1+√x+√x)*(√x-1)/(√x-1)(√x+1)=(√x+1)^2/(√x+1)=1+√x
б)(√7-√2)-5/sqrt(√7+√2)^2)=(√7-√2)-5/(√7+√2)=(7-2-5)/(√7+√2)=0
в)(a-b)(√a-√b)/(√a-√b)^2=(a-b)/(√a-√b)=√a+√b