Câu 3:
a) ($\frac{2}{5}$ + x) . 3$\frac{1}{2}$ = $\frac{-7}{2}$ <=> ($\frac{2}{5}$ + x) . $\frac{7}{2}$ = $\frac{-7}{2}$ <=> $\frac{2}{5}$ + x = -1 <=> x = $\frac{-7}{5}$
b) x - 2$\frac{3}{5}$ = $\frac{-7}{2}$ + $\frac{9}{-10}$ <=> x - $\frac{13}{5}$ = $\frac{35}{-10}$ +$\frac{9}{-10}$ <=> x - $\frac{13}{5}$ = $\frac{44}{-10}$ <=> x = -$\frac{9}{5}$
c) $\frac{30}{49}$ : (x-$\frac{1}{8}$) = $\frac{-10}{27}$ <=> x-$\frac{1}{8}$ = $\frac{30}{49}$ : $\frac{-10}{27}$ <=> x-$\frac{1}{8}$ = $\frac{-81}{49}$ <=> x = $\frac{-599}{392}$
d) $\frac{-3}{5}$x + $\frac{2}{3}$x = -$\frac{4}{15}$ <=> $\frac{-9}{15}$x + $\frac{10}{15}$x = $\frac{-4}{15}$ <=> $\frac{1}{15}$x = $\frac{-4}{15}$ <=> x = -4
Câu 6:
a) x - $\frac{-3}{4}$ = $\frac{35}{45}$ . $\frac{-9}{7}$ <=> x + $\frac{3}{4}$ = -1 <=> x = $\frac{-7}{4}$
b) $\frac{2}{7}$x + $\frac{3}{2}$ = $(\frac{-1}{2})^{2}$ - 1 <=> $\frac{2}{7}$x + $\frac{3}{2}$ = $\frac{1}{4}$ - 1 <=> $\frac{2}{7}$x + $\frac{3}{2}$ = $\frac{-3}{4}$ <=> $\frac{2}{7}$x = $\frac{-9}{4}$ <=> x = $\frac{-63}{8}$
c) $\frac{-3}{2}$x + $\frac{1}{2}$x = $\frac{5}{4}$ <=> -x = $\frac{5}{4}$ <=> x = $\frac{-5}{4}$
d) (x - 1$\frac{3}{8}$) : 20% + $\frac{1}{4}$ = 0 <=> (x - $\frac{11}{8}$) : $\frac{1}{5}$ + $\frac{1}{4}$ = 0 <=> (x - $\frac{11}{8}$) : $\frac{1}{5}$ = -$\frac{1}{4}$ <=> x - $\frac{11}{8}$ = $\frac{-5}{4}$ <=> x = $\frac{1}{8}$
P/s: Có chỗ nào ko hiểu xin hãy hỏi. Vote ctlhn nha.
