Question

giúp mình với

Bài 3: Tính và 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: \(\left(3x-2\right)^2-\left(4x-4\right)\left(2x+5\right)-x\left(x+3\right)\)

\(=9x^2-12x+4-\left(8x^2+20x-8x-20\right)-x^2-3x\)

\(=8x^2-15x+4-8x^2-12x+20=-27x+24\)

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

\(=36x^2-60x+25-\left(32x^2+12x+24x+9\right)-4x^2-5x\)

\(=32x^2-65x+25-32x^2-36x-9=-101x+16\)

Bài 4:

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

=>\(9x^2-6x+1-8x^2-4x-6x-3-x^2-x=0\)

=>-17x-2=0

=>17x+2=0

=>17x=-2

=>\(x=-\frac{2}{17}\)

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

=>\(25x^2+30x+9-20x^2-24x-10x-12=5x^2-15x\)

=>\(5x^2-4x-3=5x^2-15x\)

=>-15x=-4x-3

=>15x=4x+3

=>11x=3

=>\(x=\frac{3}{11}\)