Question

2. To complete the square of $x^2-4x$,add _______.

Short answer

To complete the square of $x^2-4x$, add 4.

Step-by-step solution

given information.

We have given quadratic expression is,$x^2-4x$.

Step 2. Concept used.

To complete the square of $x^2+bx$add ${\left(\frac{b}{2}\right)}^2$.

Step 3. Explanation.

We have given,

$x^2-4x$

To complete the square we will add third term.

Third term = localid="1646648336070" ${\left(\frac{b}{2}\right)}^2$

Comparing given expression with,

$a{x}^2+bx$we will get b is -4.

So third term = ${\left(-\frac{4}{2}\right)}^2=4$

It means to complete the square we need to add 4.

Step 4. Conclusion.

Hence, To complete the square of $x^2-4x$, add 4.