2 - 4sin^2x = 2 - 4 (1 - cos^2x) = (подставляем значение cosx = 3/4):
= 2 - 4 (1 - (3/4)^2) =
= 2 - 4 (1 - 9/16) =
= 2 - 4*7/16 =
= 2 - 7/4 = 1/4
1. 5а+2b+b = 5a+3b
2. 4x-2y+5y = 4x+3y
3. -1,2c+d-2,1d = -1,2c - 1,1d
а)(х+1)(х^2-x+1)
б)(2+c)(4-2c+c^2)
В)(z-2/3)(z^2+2/3z+4/9)
г)(a-2)(a^2+2a+4)
д)(y-x)(y^2+yx+x^2)
е)(1/3-t)(1/9+1/3t+t^2)