How do you use the quadratic formula to solve $x^2+5=4x$ ?

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Answer 1 · 2015-05-03T19:43:44

The quadratic formula:
$(-b+-sqrt(b^2-4ac))/(2a)$
can be used to find root solutions to quadratics in the form
$ax^2+bx+c = 0$

So first we need to convert the given equation into this form:
$x^2+5 = 4x$

$rarr x^2-4x+5 = 0$

Solutions are
$x= (-(-4) +- sqrt((-4)^2 -4(1)(5)))/(2(1))$

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

Since the discriminant is negative
there are no Real value solutions to this equation
but within Complex numbers, the solution is
$x=2+-i$

How do you use the quadratic formula to solve x^2+5=4xx^2+5=4x?