Question

dimitri is solving the equation $x^2 - 10x = 21$. which value must be added to both sides of the equation to make the left side a perfect - square trinomial?\
\\(\bigcirc\\) 0\
\\(\bigcirc\\) 4\
\\(\bigcirc\\) 25\
\\(\bigcirc\\) 100

Explanation:

Step1: Identify coefficient of x

The coefficient of $x$ is $-10$.

Step2: Take half the coefficient

$\frac{-10}{2} = -5$

Step3: Square the result

$(-5)^2 = 25$

Answer:

C. 25