A) =x^2+10x+25-10x+5x^2=6x^2+25
b)=16Y +2(Y^2-8Y+16)=16Y+2Y^2-8Y+32=8Y+2Y^2+32
Вроде так)
-х² - 5х² =-6х⁴ вот так................
в) а2 + ab-7a-7b = a*(a=b) - 7*(a+b)
в) 3x2 - 27 z2= 3*(x2-9z2)
№179
в) 2 c2+20cd+50 d2=2*( c2+10cd+25 d2)
S = x* y = 24;
d^2 = x^2 + y^2= 73;
x* y =24; ⇒ x =24/y;
x^2 + y^2 = 73; 576/ y^2 + y^2 = 73;
y^2 = t >0;
576 / t + t = 73;
t^2 - 73 t + 576 =0;
D = 73^2 - 4*1*576= 5329-2304 =3025=55^2;
t1= (73+55)/2=64; ⇒y^2 = 64; ⇒y = 8; ⇒x=24/8 =3;
t2=(73-55)/2= 9; ⇒ y^2 = 9; ⇒ y= 3; ⇒ x= 24/3 = 8.
P = 2( x+y) = 2( 8 + 3 ) = 2*11 = 22