Question

If using the method of completing the square to solve the quadratic equation x2 – 3x + 20 = 0, which number would have to be added to "complete the square"?​

Answer 1

Answer:

         ⁹/₄

Step-by-step explanation:

The square is:  a²-2ab+b²

We have

$x^2-3x$

it's:   $x^2-2\cdot x\cdot\frac32$

so we need:   $\left(\frac32\right)^2=\frac94$

$x^2-2\cdot x\cdot\frac32+\frac94-\frac94+20=0\\\\(x-\frac32)^2-2.25+20=0\\\\(x-\frac32)^2=-17.75$

witch, of course, means no solution