Please help me solve this quadratic equation?

3d^2-2d=8

2 Answers
May 3, 2018

3d^2-2d-8=0

d=(-(-2)+-sqrt((-2)^2-4*3*(-8)))/(2*3)

d=(2+-sqrt(100))/(6)

d=(2+-10)/(6)

d=(2+10)/(6)=(12)/(6)=2

d=(2-10)/(6)=(-8)/(6)=-8/6=-4/3

Explanation:

We can analyze the equation after we get all the numbers on one side,

3d^2-2d-8=0

From here, we can see that a=3, b=-2 and c=-8.

We now need to put it into the quadratic equation formula.

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

Which will look like,

d=(-(-2)+-sqrt((-2)^2-4*3*(-8)))/(2*3)

I have replaced x here with d, because that's what the assignment is looking for by the way.

When we do the quadratic equation, we will get the answers.

d=2 and d=-4/3

May 3, 2018

d=2 or d=-4/3

Explanation:

Here,

3d^2-2d=8

3d^2-2d-8=0

Comparing with ax^2+bx+c=0,we get

a=3,b=-2,c=-8and xtod

triangle=b^2-4ac=4-4(3)(-8)=4+96=100

sqrt(triangle)=10

So,

d=(-b+-sqrt(triangle))/(2a)=(2+-10)/(2xx3)=(2(1+-5))/(2xx3)= (1+-5)/3

=>d=(1+5)/3 or d=(1-5)/3

=>d=2 or d=-4/3