Question

[nguyen ngoc son]

1.tính nhanh các tổng sau

a) A=\(\frac{20}{19}+\frac{22}{37}+\frac{18}{43}\) và B=\(\frac{14}{39}+\frac{22}{39}+\frac{18}{41}\)

b) A=\(\frac{3}{8^3}+\frac{7}{8^4}\) và B=\(\frac{7}{8^3}+\frac{3}{8^4}\)

2.tìm x \(\in\) z biết

a) \(\frac{x-1}{6}=\frac{1}{6}\)

b) \(\frac{x-2}{5}=\frac{8}{10}\)

c) \(\frac{x-1}{8}=\frac{1}{2}\)

Answer 1

[svtkvtm]

\(\frac{x-1}{6}=\frac{1}{6}\Leftrightarrow6\left(x-1\right)=6\Leftrightarrow6x-6=6\Leftrightarrow6x=12\Leftrightarrow x=2\)

\(\frac{x-2}{5}=\frac{8}{10}=\frac{4}{5}\Leftrightarrow5\left(x-2\right)=4.5=20\Leftrightarrow5x-10=20\Leftrightarrow5x=30\Leftrightarrow x=6\)

\(\frac{x-1}{8}=\frac{1}{2}\Leftrightarrow2\left(x-1\right)=8\Leftrightarrow2x-2=8\Leftrightarrow2x=10\Leftrightarrow x=5\)

\(\text{ câu 1 mk nghĩ là so sánh chứ nhỉ?}\)