What is the solution set for $x^2 - 4x = 8$ ?

Question

5350 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-08-15T13:57:54

Refer explanation

$x^2$ - 4x - 8 = 0

Examine
$b^2$ - 4ac
$-4^2$ - ( $4 xx 1 xx -8$ ) = 16 + 32 = 48 ( positive and not a perfect square . So use formula)

x = $(-b +- sqrt(b^2 - ( 4ac )))/ (2a)$

x = $(-(-4) +- sqrt((-4)^2 - ( 4 xx 1 xx -8 )))/ (2 xx 1)$

x = $(4+- sqrt((16 - ( -32 ))))/ (2)$

x = $(4+- sqrt(16 + 32 ))/ (2)$

x = $(4+- sqrt(48 ))/ (2)$

x = $(4+- 6.9 )/ (2)$
x = $(4+ 6.9 )/ (2)$ = 5.45

x = $(4- 6.9 )/ (2)$ = - 1.45

What is the solution set for x^2 - 4x = 8x^2 - 4x = 8?