How do you solve $- 5 x^{2} + 5 x + 60 = 0$ $-5x^2 + 5x + 60 = 0$ using the quadratic formula?

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Answer 1 · 2015-08-12T06:03:46

The solutions are
$x = - 3, x = 4$ $color(blue)(x=-3, x=4$

$- 5 x^{2} + 5 x + 60 = 0$ $−5x^2+5x+60=0$

The equation is of the form $a x^{2} + b x + c = 0$ $color(blue)(ax^2+bx+c=0$ where:
$a = - 5, b = 5, c = 60$ $a=-5, b=5, c=60$

The Discriminant is given by:

$color(blue)(Delta=b^2-4*a*c$

$= (5)^2-(4*(-5)*60)$

$= 25 + 1200=1225$

The solutions are found using the formula:

$color(blue)(x=(-b+-sqrtDelta)/(2*a)$

$x = ((-5)+-sqrt(1225))/(2*(-5)) = ((-5+-35))/-10$

Solution 1:

$x=(-5+35)/-10 = 30/(-10)$

$color(blue)(x=-3$

Solution 2:

$x=(-5-35)/-10 = -40/-10$

$color(blue)(x=4$

How do you solve -5x^2 + 5x + 60 = 0−5x2+5x+60=0-5x^2 + 5x + 60 = 0 using the quadratic formula?