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24 tháng 1 2017

\(Q=\frac{12x^2+20x+3}{6x^2+43x+7}=\frac{12x^2+18x+2x+3}{6x^2+42x+x+7}=\frac{6x\left(2x+3\right)+\left(2x+3\right)}{6x\left(x+7\right)+\left(x+7\right)}=\frac{\left(6x+1\right)\left(2x+3\right)}{\left(6x+1\right)\left(x+7\right)}=\frac{2x+3}{x+7}\)\(P=\frac{8x^2+36x+36}{x^2+10x+21}=\frac{4\left(2x^2+9x+9\right)}{x^2+3x+7x+21}=\frac{4\left(2x^2+3x+6x+9\right)}{x\left(x+3\right)+7\left(x+3\right)}=\frac{4\left[x\left(2x+3\right)+3\left(2x+3\right)\right]}{\left(x+3\right)\left(x+7\right)}=\frac{4\left(x+3\right)\left(2x+3\right)}{\left(x+3\right)\left(x+7\right)}=\frac{4\left(2x+3\right)}{x+7}\)

=> \(Q:P=\frac{2x+3}{x+7}:\frac{4\left(2x+3\right)}{x+7}=\frac{2x+3}{x+7}.\frac{x+7}{4\left(2x+3\right)}=\frac{1}{4}\)

=>\(Q=\frac{1}{4}P\)

24 tháng 1 2017

\(\frac{Q\left(0\right)}{P\left(0\right)}=\frac{3.21}{7.36}=\frac{1}{4}\Rightarrow Q=\frac{1}{4}P\)

22 tháng 11 2015

\(Q=\frac{\left(6x+1\right)\left(2x+3\right)}{\left(6x+1\right)\left(x+7\right)}=\frac{2x+3}{x+7}\)

\(P=\frac{4\left(2x+3\right)\left(x+3\right)}{\left(x+7\right)\left(x+3\right)}=\frac{4\left(2x+3\right)}{x+7}=4Q\)

\(\frac{P}{Q}=4\)

20 tháng 9 2018

1) 12x3 - 43x2 - 20x +3

= x( 12x2- 43x -20 ) + 3

=x[x(12x-43-20]+3

=x[x(12x-63)]+3

2) x3+4x2-11x-30

= x(x2+4x-11)-30

= x[x(x+4-11)]-30

= x[x(x-7)] - 30

3) x3+3x2-2

= x2(x+3)-2

2: \(=x^3-3x^2+7x^2-21x+10x-30\)

\(=\left(x-3\right)\left(x^2+7x+10\right)\)

\(=\left(x-3\right)\left(x+2\right)\left(x+5\right)\)

3: \(=x^3+x^2+2x^2-2\)

\(=x^2\left(x+1\right)+2\left(x-1\right)\left(x+1\right)\)

\(=\left(x+1\right)\cdot\left(x^2+2x-2\right)\)