\(3\left(2-x\right)+5\left(x-6\right)=-98\)

\(\Rightarrow6-3x+5x-30=-98\)

\(\Rightarrow2x-24=-98\)

\(\Rightarrow2x=-74\)

\(\Rightarrow x=-37\)

a: \(\frac{4}{15}:\frac47

=>\(\frac{4}{15}\times\frac74

=>\(\frac{7}{15}

b: Cách 1: \(\frac35\times\frac37+\frac25\times\frac47\)

\(=\frac{3\times3+2\times4}{5\times7}=\frac{9+8}{35}=\frac{17}{35}\)

Cách 2:

Ta có: \(\frac35\times\frac37+\frac25\times\frac47\)

\(=\frac15\times\frac17\times\left(3\times3+2\times4\right)\)

\(=\frac{1}{35}\times\left(9+8\right)=\frac{17}{35}\)

a) \(\frac{3}{2}-\frac{5}{6}:x=\frac{5}{15}-\frac{3}{15}\)

\(\Leftrightarrow\frac{3}{2}-\frac{5}{6}:x=\frac{2}{15}\)

\(\Leftrightarrow\frac{5}{6}:x=\frac{3}{2}-\frac{2}{15}\)

\(\Leftrightarrow\frac{5}{6}:x=\frac{41}{30}\)

\(\Leftrightarrow x=\frac{5}{6}:\frac{41}{30}\)

\(\Leftrightarrow x=\frac{25}{41}\)

b) \(x-\frac{6}{7}.\frac{14}{8}=\frac{1}{2}-\frac{2}{5}\)

\(\Leftrightarrow x-\frac{3}{2}=\frac{1}{10}\)

\(\Leftrightarrow x=\frac{1}{10}+\frac{3}{2}\)

\(\Leftrightarrow x=\frac{8}{5}\)

c) \(x:\frac{6}{5}+\frac{2}{3}=\frac{7}{3}\)

\(\Leftrightarrow x:\frac{6}{5}=\frac{7}{3}-\frac{2}{3}\)

\(\Leftrightarrow x:\frac{6}{5}=\frac{5}{3}\)

\(\Leftrightarrow x=\frac{5}{3}.\frac{6}{5}\)

\(\Leftrightarrow x=2\)

huyền ngốc

  \(\dfrac{3}{4}\cdot\dfrac{2}{5}-\dfrac{3}{4}\cdot\dfrac{2}{7}\)

= \(\dfrac{3}{4}\cdot\left(\dfrac{2}{5}-\dfrac{2}{7}\right)\)

= \(\dfrac{3}{4}\cdot\left(\dfrac{14}{35}-\dfrac{10}{35}\right)\)

= \(\dfrac{3}{4}\cdot\dfrac{4}{35}\)

= \(\dfrac{3}{35}\)

bạn ghi + - x : nhá

812 x 5 + 812 x 7 - 7 - 812 x 2 ???

 toàn câu hỏi sai

\(a.2^6.\left(x-2\right)=104\)

\(x-2=104:2^6\)

\(x-2=1,652\)

\(x=1,625+2\)

\(x=3,625\)

\(b.2\times4^{x+1}=128\)

\(4^{x+1}=128:2\)

\(4^{x+1}=64\)

\(4^{x+1}=4^3\)

\(\Rightarrow x+1=3\)

\(x=3-1\)

\(\Leftrightarrow x=3\)

\(c.227-5\left(x+8\right)=3^6:3^3\)

\(227-5\left(x+8\right)=3^3\)

\(227-5\left(x+8\right)=27\)

\(5\left(x+8\right)=227-27\)

\(5\left(x+8\right)=200\)

\(x+8=200:5\)

\(x+8=40\)

\(x=40-8\)

\(x=32\)

ủng hộ mk nha, chắc đúng đó

cả tháng nay ms online lại

thx bn