Answer:
Step-by-step explanation:
The square is: a²-2ab+b²
We have
[tex]x^2-3x[/tex]
it's: [tex]x^2-2\cdot x\cdot\frac32[/tex]
so we need: [tex]\left(\frac32\right)^2=\frac94[/tex]
[tex]x^2-2\cdot x\cdot\frac32+\frac94-\frac94+20=0\\\\(x-\frac32)^2-2.25+20=0\\\\(x-\frac32)^2=-17.75[/tex]
witch, of course, means no solution