Đáp án:
Giải thích các bước giải:
`a)`
`5x^2 - 7x + 2 = 0`
`-> (5x^2-2x)+(-5x+2) = 0`
`-> x(5x-2) - (5x-2) = 0`
`-> (5x-2)(x-1) = 0`
`->` \(\left[ \begin{array}{l}5x-2=0\\x-1=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=\dfrac25\\x=1\end{array} \right.\)
Vậy `x \in {2/5,1}`
`b)`
`2x^2 - 9x - 11 = 0`
`-> (2x^2+2x)+(-11x-11) = 0`
`-> 2x(x+1) - 11(x+1) = 0`
`-> (x+1)(2x-11) = 0`
`->`\(\left[ \begin{array}{l}x+1=0\\2x-11=0\end{array} \right.\)
`->`\(\left[ \begin{array}{l}x=-1\\x=\dfrac{11}2\end{array} \right.\)
Vậy `x \in {-1,11/2}`
`c)`
`2x^2-5x+3=0`
`-> (2x^2-2x) + (-3x+3) = 0`
`-> 2x(x-1) - 3(x-1) = 0`
`-> (x-1)(2x-3) = 0`
`->`\(\left[ \begin{array}{l}x-1=0\\2x-3=0\end{array} \right.\)
`->`\(\left[ \begin{array}{l}x=1\\x=\dfrac32\end{array} \right.\)
Vậy `x \in {1,3/2}`
