Question

giúp mình với ạ

Bài 3: Tính rồi thu gọn

1) \((3x - 2)^2 - (4x - 1) \cdot (2x + 5) - x(x + 3)\)

2) \((6x - 5)^2 - (4x + 3) \cdot (8x + 3) - 6x(4x + 5)\)

Bài 4: Tìm x

1) \((3x - 1)^2 - (4x + 3) \cdot (2x + 1) - x(x + 1) = 0\)

2) \((5x + 3)^2 - (4x + 2) \cdot (5x + 6) = 5x(x - 3)\)

Answer 1

bài 3:

\(1.\left(3x-2\right)^2-\left(4x-1\right)\cdot\left(2x+5\right)-x\cdot\left(x+3\right)\)

\(=9x^2-12x+4-8x^2-18x+5-x^2-3x\)

\(=9-33x\)

\(2.\left(6x-5\right)^2-\left(4x+3\right)\cdot\left(8x+3\right)-x\cdot\left(4x+5\right)\)

\(=36x^2-60x+25-32x^2-36x-9-4x^2-5x\)

\(=16-101x\)

bài 4:

\(1.\left(3x-1\right)^2-\left(4x+3\right)\cdot\left(2x+1\right)-x\cdot\left(x+1\right)=0\)

\(9x^2-6x+1-8x^2-10x+3)-x^2-x=0\)

\(-17x-2=0\Rightarrow x=-\frac{2}{17}\)

\(2.\left(5x+3\right)^2-\left(4x+2\right)\left(5x+6\right)=5x\left(x-3\right)\)

\(25x^2+30x+9-20x^2-34x-12-5x^2+15x=0\)

\(11x-3=0\Rightarrow x=\frac{3}{11}\)