1) х/2-7= (х-14)/2
2) (х-14)/2 = (12-5х)/13
13х-182 = 24-10х
13х+10х = 24+182
23х = 206
х = 8,9
чет не вышло.. извиняюсь, решила, как смогла...
Sin x * sin y = 1/2 (cos (x-y) - cos(x+y))
cos (x-y) - cos(x+y) = sqrt(3)/2
cosx * cosy = 1/2 (cos (x-y) + cos(x+y))
cos (x-y) + cos(x+y) = sqrt(3)/2
2 * cos(x-y) = sqrt(3)
cos(x-y) = sqrt(3)/2
x-y = +- (pi/6) + 2pi * k
справишься дальше?
<span>(x+4)^2-(x+1)(x-2)=2x-3
x^2+8x+16 - (x^2 - x - 2) - 2x + 3 = 0
x^2 + 8x + 16 - x^2 +x + 2 - 2x + 3 = 0
7x + 21 = 0
7x = - 21
x = - 3 </span>
(2 2/3 + х) : 2 = 3
2 2/3 + х = 6
х = 6 - 2 2/3
х = 3 1/3