Answer:
Option C is correct.
A number is, 25
Step-by-step explanation:
To complete the square of the given equation: [tex]x^2+10x = 8[/tex]
Take half of the value of the term containing x then square it,
and add and subtract that value from the left-hand side of the equation.
It should be done in the following manner:
[tex]x^2+10x+(5)^2- (5)^2= 8[/tex]
Now, use the middle-term break to factories the expression within the parenthesis,
[tex](x^2+10x+5^2)-25= 8[/tex]
Use the algebraic identity: [tex](a+b)^2 = a^2+2ab+b^2[/tex]
we have;
[tex](x+5)^2 -25=8[/tex]
Add 25 to both sides we get;
[tex](x+5)^2=33[/tex]
Therefore, you add a number 25 to complete the square.
