Question

What are the roots of the equation 3x^2+5x=8

Answer 1

Subtract both sides by 8, then use quadratic formula.

Answer 2

Whats the formula? What i did was subtract then factored to (2x+5)(x+1)

Answer 3

Ah, or you can factor it. You did it, now find the x. You know how to?

Answer 4

I think i have but i dont know if its correct i got x > -2.5 && x > - 1

Answer 5

it is (-8/3) and 1

Answer 6

i used my graphing calculator application to find it

Answer 7

I dont just want the answer i want to know how to do it

Answer 8

use the quadratic formular

Answer 9

what does it mean? @micahwood50

Answer 10

Don't listen to him, (2x+5)(x+1) = 0 so either (2x+5) or (x+1) is equal to zero so x can be -1 for (x+1) to be zero and x also can be -5/2 or -2.5

Answer 11

@micahwood50 factoring was not done correctly.
if aske needs quadratic formula, then here it is:
Compare your quadratic equation with \(ax^2+bx+c=0\)
find a,b,c
then the two roots of x are:
\(\huge{x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}}\)

Answer 12

\[\frac{ -b \pm \sqrt{{b}^2-4ac} }{ 2a }\]

Answer 13

then it is 3x^2 +5x -8=0
a=3
b=5
c=-8

Answer 14

now substitute the values in

Answer 15

\[\frac{ -5 \pm \sqrt{{5}^2-4(3)(-8)} }{2(3) }\]

Answer 16

thanks man

Answer 17

now calculate
\[\frac{ -5\pm \sqrt{25-4(-24)} }{ 6 }\]

Answer 18

you got the idea now

Answer 19

i plugged in and it doesnt work

Answer 20

"Whats the formula? What i did was subtract then factored to (2x+5)(x+1)"

Would of worked if you had factored correctly.
Factors to (x-1)(3x+8)=0
x=1
x=-8/3

Answer 21

Factoring if possible, is simpler than quadratic formula, but, factoring is not always simple!

Answer 22

........and not always possible lol

Answer 23

@leanswag , the question is still open, are you still having problems with it?