Question

 

help me câu c,d 

hhel 

Answer 1

\(x_1+x_2=-\dfrac{b}{a}=3;x_1x_2=\dfrac{c}{a}=1\)

c: \(\dfrac{1-x_1}{x_1}+\dfrac{1-x_2}{x_2}\)

\(=\dfrac{1}{x_1}+\dfrac{1}{x_2}-1-1\)

\(=\dfrac{x_1+x_2}{x_1x_2}-2=\dfrac{3}{1}-2=3-2=1\)

d: \(\dfrac{x_1}{x_2+1}+\dfrac{x_2}{x_1+1}\)

\(=\dfrac{x_1\left(x_1+1\right)+x_2\left(x_2+1\right)}{\left(x_1+1\right)\left(x_2+1\right)}\)

\(=\dfrac{x_1^2+x_2^2+\left(x_1+x_2\right)}{x_1x_2+\left(x_1+x_2\right)+1}\)

\(=\dfrac{\left(x_1+x_2\right)^2+\left(x_1+x_2\right)-2x_1x_2}{x_1x_2+\left(x_1+x_2\right)+1}\)

\(=\dfrac{3^2+3-2\cdot1}{1+3+1}=\dfrac{9+3-2}{5}=\dfrac{10}{5}=2\)