Question

Which of the following constants can be added to x2 - 3x to form a perfect square trinomial?

Answer 1

ANSWER

$2 \frac{1}{4}$

EXPLANATION

We want to find the constant that must be added to

${x}^{2} - 3x$

to form a perfect square.

Comparing the given expression to

$a{x}^{2} + bx + c$

we have

a=1 , b=-3 , and c=0.

We need to add

${( \frac{b}{2a} })^{2}$

We substitute the values to get,

${( \frac{ - 3}{2(1)} })^{2} = \frac{9}{4}$

We change this to mix numbers to get,

$2 \frac{1}{4}$

The last choice is correct.