S=0.5*7*7SIN150градус=0,5*49*SIN30градус=24.5*0.5=12.25
Ответ:12.25
(x+5)^2=(x-3)^2
x^2+10x+25=x^2-6x+9
16x=-16
x=1
1.
a) 22 -6x +4 =7x
26 -6x -7x =0
-13x = -26
x=2
b) 15x -14x -35 =4x +4
x -35 -4x -4 =0
-3x -39=0
-3x =39
x= -13
2.
2a²+2ax-2ay-2ax+2xy+2x²+3ay-3xy+3y² =
=2a²+2x²+3y² +ay-xy
(0,8x+y)*(y-0,8x)= -0,64x^2+y^2. Ответ: -0,64x^2+y^2.