Question

Answer 1

\(a,x=3\Leftrightarrow9-12+m+1=0\Leftrightarrow m=2\\ b,\text{PT có 2 nghiệm pb }\Leftrightarrow\Delta'=4-\left(m+1\right)>0\\ \Leftrightarrow m< 3\\ \text{Viét: }\left\{{}\begin{matrix}x_1+x_2=4\\x_1x_2=m+1\end{matrix}\right.\\ \dfrac{x_1}{x_2}+\dfrac{x_2}{x_1}=1\\ \Leftrightarrow\dfrac{x_1^2+x_2^2}{x_1x_2}=1\\ \Leftrightarrow x_1^2+x_2^2-x_1x_2=0\\ \Leftrightarrow\left(x_1+x_2\right)^2-3x_1x_2=0\\ \Leftrightarrow16-3m-3=0\\ \Leftrightarrow m=\dfrac{13}{3}\left(ktm\right)\Leftrightarrow m\in\varnothing\)

Answer 2

a,x=3⇔9−12+m+1=0⇔m=2b,PT có 2 nghiệm pb ⇔Δ′=4−(m+1)>0⇔m<3Viét: {x1+x2=4x1x2=m+1x1x2+x2x1=1⇔x21+x22x1x2=1⇔x21+x22−x1x2=0⇔(x1+x2)2−3x1x2=0⇔16−3m−3=0⇔m=133(ktm)⇔m∈∅

nha