bài 1: thực hiện phép tính:
a) 4x \(\left(\dfrac{2}{3}x-1\right)\) + \(\left(12x^2-3x\right)\) : (-3x) - \(\left(2x+1\right)^2\)
b) (x + 3y)(\(x^2\) -2xy + y)
c) \(\left(x+1\right)^3\) - x\(\left(x-2\right)^3\) - 1
d) \(\left(x-1\right)^3\) - (x+2) (\(x^2\) - 2x+ 4) + 3 (x+4) (x-4)
e) (y - 3) (y + 3) (\(y^2\) + 9) - (\(y^2\) + 2) (\(y^2\) -2)
bài 2: phân tích đa thức thành nhân tử:
a) \(\left(xy+1\right)^2\) - \(\left(x-y\right)^2\)
b) \(x^2\) - \(4y^4\) + x + 2y
c) \(\left(x^2+2x\right)^2\) + \(9x^2\) + 18x
d) (x+2) (x+4) (x+6) (x+8) +16
e) \(x^3\) + 27 + (x + 3) (x-9)
f) \(\left(x-y+4\right)^2\) - \(\left(2x+3y-1\right)^2\)
bài 3: tìm x:
a) 2\(x^3\) - 5x = 0
b) 5x (x-2) - (2-x) = 0
c) 3 \(\left(x-5\right)^2\) - 3x (\(x^2\) -25) = 0
d) \(\left(x+3\right)^2\) - (x-4) (x+3) = -4
e) \(4x^2\) - 4x + 1 = 4
f) (x - 1) (\(x^2\) + x+ 1) - x (x+ 2) (x - 2) = 0
g) \(x^2\) + x = 6