Question

tim so nguyen x: -28-7.\(\left|-3x+15\right|\)=-70

Answer 1

b) -28-7.|-3x+15| = -70

⇔ 7.|-3x+15| = 42

⇔ |-3x+15| = 6

\(\Leftrightarrow\left[{}\begin{matrix}\text{-3x + 15 = 6 }\\\text{-3x + 15 = -6 }\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=7\\x=3\end{matrix}\right.\)

Answer 2

-28-7.|-3x+15|=-70

-7.|-3x+15|=-70+28

-7.|-3x+15|=-42

|-3x+15|=-42:(-7)

|-3x+15|=6

=>-3x+15=6 hoặc -3x+15=-6

TH1: -3x +15=6

-3x=6-15

-3x=-9

x=-9:(-3)

x=3

TH2: -3x+15=-6

-3x=-6-15

-3x=-21

x=-21:(-3)

x=7

Vậy x {3;7}

Answer 3

\(-28-7|-3x+15|=-70\)

\(\Leftrightarrow7|-3x+15|=42\)

\(\Leftrightarrow\left|-3x+15\right|=6\)

\(\Leftrightarrow\left[{}\begin{matrix}-3x+15=6\\-3x+15=-6\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}-3x=-9\\-3x=-21\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=7\end{matrix}\right.\)

Vậy ...............................

Answer 4

Tick cho mk nha