Đáp án+Giải thích các bước giải:
Bài 2:
`b,4/13*-5/17+ -12/13*4/17 +4/13`
`=4/13(-5/17+ -12/17 +1)`
`=4/13 * 0`
`= 0`
Bài 3:
`a,2 3/7x-75%=-0,25`
`<=>17/7x-3/4=-1/4`
`<=>17/7x=1/2`
`<=>x=7/34`
Vậy `x=7/34`
`b,|-1/2+x^2|=7/2`
`<=>` \(\left[ \begin{array}{l}\frac{-1}{2}+x^2=\frac{7}{2}\\\frac{-1}{2}+x^2=\frac{-7}{2}\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x^2=4\\x^2=-3\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}\left\{ \begin{array}{l}x=2\\x=-2\end{array} \right. \\x=∅\end{array} \right.\)
Vậy `x=2` hoặc `x=-2`
