Tìm x

Bài 9: Tìm x, biết: a) 3(x+2)2 + (2x–1)2 –7(x–3)(x+3) = 36 b) (x–1)(x2+x+1) –x(x+2)(x–2) = 5 c) (x–1)3 – (x+3)(x2–3x+9) + 3(x2–4) = 2