Trả lời:
a, Đổi: 75%=$\frac{3}{4}$
=> $\frac{3}{8}$ +$\frac{5}{8}$x= $\frac{3}{4}$
=> $\frac{5}{8}$x=$\frac{3}{4}$-$\frac{3}{8}$
=>$\frac{5}{8}$x= $\frac{3}{8}$
=> x=$\frac{3}{8}$:$\frac{5}{8}$ => x=$\frac{3}{5}$
b, = (x+$\frac{7}{2}$ )$^{2}$ =$\frac{1}{20}$+$\frac{1}{5}$
=> (x+$\frac{7}{2}$ )$^{2}$ =$\frac{1}{4}$
=> \(\left[ \begin{array}{l}x+\frac{7}{2}= \frac{-1}{2} \\x+\frac{7}{2}=\frac{1}{2} \end{array} \right.\)
=>\(\left[ \begin{array}{l}x=\frac{-1}{2}-\frac{7}{2} \\x=\frac{1}{2}-\frac{7}{2} \end{array} \right.\)
=> \(\left[ \begin{array}{l}x=-4\\x=-3 \end{array} \right.\)
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