solve:
sin^2x - sinx = 2, -pi </= x </= 0
solution must be in exact form
sin^2x - sinx - 2 = 0
factoring ... (sinx - 2) (sinx + 1) = 0
sinx - 2 = 0 ... sinx = 2 ... spurious solution
sinx + 1 = 0 ... sinx = -1 ... x = -π / 2
sin^2x - sinx = 2, -pi </= x </= 0
solution must be in exact form
factoring ... (sinx - 2) (sinx + 1) = 0
sinx - 2 = 0 ... sinx = 2 ... spurious solution
sinx + 1 = 0 ... sinx = -1 ... x = -π / 2