<span>А)(5а-b)^2=25a</span>²-10ab+b²<span>
b)(y+6)^2=y</span>²+12y+36<span>
B)(5a-2)(5a+2)=25a</span>²-4<span>
Г)(x-0,6)(0,6+x)=x</span>²-0,36
160/x-160/(x+16)=1/3
(160(x+16)-160x)/(x(x+16))=1/3
160x+2560-160x/x(x+16)=1/3
7680=x^2+16x
x^2+16x-7680=0 ( делим на 16)
x^2/16+x-480=0
D=b^2-4ac=1+1/16*4*480=121
x1=-b-√D/2a=-1-11/(2*1/16)=-96
x2=-b+√D/2a=-1+11/(2*1/16)=10/0.125=80
ответ: x1=-96; x2=80
X²+x√10-25-(x²-25)=x²+x√10-25-x²+25=x√10
При х=√40 √40√10=√40*10=√400=20