Question

$${ \left(-x+4 \right) }^{ 2 } =256$$

Answer

x=-12,20

Solution


Regroup terms.
\[{(4-x)}^{2}=256\]
Take the square root of both sides.
\[4-x=\pm \sqrt{256}\]
Since \(16\times 16=256\), the square root of \(256\) is \(16\).
\[4-x=\pm 16\]
Break down the problem into these 2 equations.
\[4-x=16\]
\[4-x=-16\]
Solve the 1st equation: \(4-x=16\).
\[x=-12\]
Solve the 2nd equation: \(4-x=-16\).
\[x=20\]
Collect all solutions.
\[x=-12,20\]