Tìm x, biếttìm x,biết a) 16x^2 - (4x-5)^2 = 15 b) (2x+3)^2 - 4(x-1)(x+1) = 49 c) (2x+1)(1-2x)+(1-2x)^2 = 18 d) 2(x+1)^2 - (x-3)(x+3)-(x-4)^2 = 0 e) (x-5)^2 - x(x-4) = 9 f) (x-5)^2 + (x-4)(1-x) = 0 |