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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"?​

Sagot :

Answer:

         ⁹/₄

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