How do you solve $x^2 - x = 42$ ?

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Answer 1 · 2016-03-15T15:21:05

The solutions are:
$x = 7$

$x=-6$

$x^2 - x =42$

$x^2 - x - 42 =0$

The equation is of the form $color(blue)(ax^2+bx+c=0$ where:

$a=1, b=-1, c=-42$

The Discriminant is given by:

$Delta=b^2-4*a*c$

$= (-1)^2-(4*1* -42)$

$= 1 + 168=169$

The solutions are found using the formula
$x=(-b+-sqrtDelta)/(2*a)$

$x = (-(-1)+-sqrt(169))/(2*1) = (1+-13)/2$

$x= (1+13)/2 = 14/2 = 7$

$x= (1-13)/2 = -12/2 =-6$

How do you solve x^2 - x = 42x^2 - x = 42?