Bài 10:
2: 4(x+2)-7(2x-1)+9(3x-4)=30
=>\(4x+8-14x+7+27x-36=30\)
=>17x-21=30
=>17x=51
=>x=3
3: \(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)
=>10x-16-12x+15=12x-16+11
=>-2x-1=12x-5
=>-14x=-5+1=-4
=>\(x=\dfrac{4}{14}=\dfrac{2}{7}\)
4: \(3x\left(x-2\right)-3\left(x^2+1\right)=x^2+1-x\left(x-2\right)\)
=>\(3x^2-6x-3x^2-3=x^2+1-x^2+2x\)
=>-6x-3=2x+1
=>-8x=4
=>\(x=-\dfrac{1}{2}\)
5: \(5\left(3x+5\right)-4\left(2x-3\right)=5x+3\left(3x+12\right)\)
=>15x+25-8x+12=5x+9x+36
=>7x+37=14x+36
=>-7x=-1
=>\(x=\dfrac{1}{7}\)
6: \(\left(7x+7\right)+3x\left(2x-1\right)-2x\left(3x+15\right)=-4\)
=>\(7x+7+6x^2-3x-6x^2-30x=-4\)
=>-26x=-11
=>\(x=\dfrac{11}{26}\)
Bài 11:
1: \(\left(3x-1\right)\left(2x+7\right)-\left(x+1\right)\left(6x-5\right)=7\)
=>\(6x^2+21x-2x-7-6x^2+5x-6x+5=7\)
=>18x-2=7
=>18x=9
=>\(x=\dfrac{1}{2}\)
2: \(\left(3x+2\right)\left(2x+9\right)-\left(x+2\right)\left(6x+1\right)=7\)
=>\(6x^2+27x+4x+18-6x^2-x-12x-2=7\)
=>18x+16=7
=>18x=-9
=>\(x=-\dfrac{1}{2}\)
3: \(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)
=>\(48x^2-12x-20x+5+3x-48x^2-7+112x=81\)
=>83x-2=81
=>83x=83
=>x=1
4: \(2\left(3x-1\right)\left(2x+5\right)-6\left(2x-1\right)\cdot\left(x+2\right)=-6\)
=>\(2\left(6x^2+15x-2x-5\right)-6\left(2x^2+4x-x-2\right)=-6\)
=>\(2\left(6x^2+13x-5\right)-6\left(2x^2+3x-2\right)=-6\)
=>\(12x^2+26x-10-12x^2-18x+12=-6\)
=>8x+2=-6
=>8x=-8
=>x=-1
