a)\(3x^2-8x+4\)
\(=3x^2-2x-6x+4\)
\(=x\left(3x-2\right)-2\left(3x-2\right)\)
\(=\left(x-2\right)\left(3x-2\right)\)
b)\(3x^2-16x+5\)
\(=3x^2-x-15x+5\)
\(=x\left(3x-1\right)-5\left(3x-1\right)\)
\(=\left(x-5\right)\left(3x-1\right)\)
c)\(2x^2-5x-12\)
\(=2x^2+3x-8x-12\)
\(=x\left(2x+3\right)-4\left(2x+3\right)\)
\(=\left(x-4\right)\left(2x+3\right)\)
d)\(8x^2+30x+7\)
\(=8x^2+2x+27x+7\)
\(=2x\left(4x+1\right)+7\left(4x+1\right)\)
\(=\left(2x+7\right)\left(4x+1\right)\)
e)\(6x^2-7x-20\)
\(=6x^2+8x-15x-20\)
\(=2x\left(3x+4\right)-5\left(3x+4\right)\)
\(=\left(2x-5\right)\left(3x+4\right)\)
a, \(3x^2-8x+4=3x^2-6x-2x+4\)
\(=3x.\left(x-2\right)-2.\left(x-2\right)=\left(x-2\right).\left(3x-2\right)\)
b, \(3x^2-16x+5=3x^2-15x-x+5\)
\(=3x.\left(x-5\right)-\left(x-5\right)=\left(x-5\right).\left(3x-1\right)\)
c, \(2x^2-5x-12=2x^2-8x+3x-12\)
\(=2x.\left(x-4\right)+3.\left(x-4\right)=\left(x-4\right).\left(2x+3\right)\)
d, \(8x^2+30x+7=8x^2+2x+28x+7\)
\(=2x.\left(4x+1\right)+7.\left(4x+1\right)=\left(4x-1\right).\left(2x+7\right)\)
e, \(6x^2-7x-20=6x^2-15x+8x-20\)
\(=3x.\left(2x-5\right)+4x.\left(2x-5\right)=\left(2x-5\right).\left(3x+4x\right)\)
Chúc bạn học tốt!!!
a) \(3x^2-8x+4=\left(x-2\right)\left(3x-2\right)\)
b) \(3x^2-16x+5=\left(x-5\right)\left(3x-1\right)\)
c) \(2x^2-5x-12=\left(x-4\right)\left(3x+2\right)\)
d) \(8x^2+30x+7=\left(4x+1\right)\left(2x+7\right)\)
e) \(6x^2-7x-20=\left(2x-5\right)\left(3x+4\right)\)
Mấy cái này bấm máy nhanh không í mà