How do you solve by completing the square: $x^2+3x-4=0$ ?

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Answer 1 · 2015-04-03T17:18:28

x=1 , -4
Take half of the coefficient of x, that would be $3/2$ in this case. Square this number and add it and subtract it as shown below.

$x^2$ +3x + $9/4$ - $9/4$ -4=0

$(x+3/2)^2$ = $25/4$ . Take square root of both sides to have x+ $3/2$ = $5/2$ or $-5/2$

x+ $3/2$ = $5/2$ would give x= $5/2$ - $3/2$ = 1 and

X+ $3/2$ = $-5/2$ would give x= $-5/2$ $-3/2$ = -4

How do you solve by completing the square: x^2+3x-4=0x^2+3x-4=0?