Question

86:[2.(2x-1)²-7]+4²=2.3²

Answer 1

\(\frac{86}{\left[2.\left(2x-1\right)^2-7\right]}+4^2=2.3^2\Leftrightarrow\frac{86}{\left[2.\left(2x-1\right)^2-7\right]}=2.9-4^2=2\)

\(\frac{86}{2}=\left[2.\left(2x-1\right)^2-7\right]=2.\left(2x-1\right)^2-7\)

\(43=2.\left(2x-1\right)^2-7\Leftrightarrow2.\left(2x-1\right)^2=43+7=50\)

\(\left(2x-1\right)^2=\frac{50}{2}=25=5^2\Rightarrow!2x-1!=5\)

\(\orbr{\begin{cases}2x-1=-5\\2x-1=5\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=-4\\2x=6\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=3\end{cases}}}}\)

Answer 2

x=3 hoặc x=-2, cứ tính từ từ rồi chuyển vế.