Question

Bài 10 : Tìm x  \(\in\)Z , biết :

a,        \(\left|2x+1\right|-19=-7\)

b,       \(-28-7\cdot\left|-3x+15\right|=-70\)

c,        \(12-2\left(-x+3\right)^2=-38\)

d,         \(-20+3\cdot\left(2x+1\right)^3=-101\)

Answer 1

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

\(\Rightarrow7.|-3\chi+15|=42\)

\(\Rightarrow|-3\chi+15|=6\)

\(\Rightarrow\orbr{\begin{cases}-3\chi+15=6\\-3\chi+15=-6\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}-3\chi=-9\\-3\chi=-21\end{cases}}\Rightarrow\orbr{\begin{cases}\chi=3\\\chi=7\end{cases}}\)

HTDT

Answer 2

\(c,12-2\left(-\chi+3\right)^2=-38\)

\(\Rightarrow2\left(-\chi+3\right)^2=50\)

\(\Rightarrow\left(-\chi-3\right)^2=25\)

\(\Rightarrow\left(-\chi-3\right)^2=\left(\pm5\right)^2\)

\(\Rightarrow\orbr{\begin{cases}-\chi-3=5\\-\chi-3=-5\end{cases}}\Rightarrow\orbr{\begin{cases}\chi=-8\\\chi=-2\end{cases}}\)

HTDT

Answer 3

cau d tuong tu cau c, nha!!

kkk

Answer 4

a,\(\left|2x+1\right|-19=-7\)

\(\Rightarrow\left|2x+1\right|=2\)

\(\Rightarrow\orbr{\begin{cases}2x+1=2\\2x+1=-2\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=-\frac{3}{2}\end{cases}}}\)

b,\(-18-7\left|-3x+15\right|=-70\)

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

\(\Rightarrow\orbr{\begin{cases}3x+15=6\\3x+15=-6\end{cases}\Rightarrow\orbr{\orbr{\begin{cases}x=-3\\x=-7\end{cases}}}}\)