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

2 Answers
Aug 13, 2016

x={0,-5/2}

Explanation:

ax^2+bx+c=0

2x^2+5x=0

a=2" ; "b=5" ; "c=0

Delta=sqrt(b^2-4*a*c)

Delta=sqrt(5^2-4*2*0)

Delta=sqrt 5^2

Delta=±5

x_("1,2")=(-b±Delta)/(2*a)

x_1=(-5-5)/(2*2)=-10/4=-5/2

x_2=(-5+5)/(2*2)=0

x={0,-5/2}

"Or simply"

2x^2+5x=0

2cancel(x^2)=-5cancel(x)

2x=-5

x=-5/2

Aug 13, 2016

x=-5/2, 0

Explanation:

2x^2+5x=0 is a quadratic equation in the form ax^2+bx+c, where a=2, 5=b, and c=0.

Quadratic formula

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

Plug the given values into the formula.

x=(-5+-sqrt((-5)^2-4*2*0))/(2*2)

Simplify.

x=(-5+-sqrt(25-0))/4

Simplify.

x=(-5+-sqrt 25)/4

Simplify.

x=(-5+-5)/4

Solve for x_1 and x_2.

color(blue)(x_1=(-5+5)/4)

color(blue)(x_1=0/4)

color(blue)(x_1=0)

color(red)(x_2=(-5-5)/4)

color(red)(x_2=-10/4)

color(red)(x_2=-5/2)

color(purple)(x=-5/2, 0)