What is the positive root of the equation 3x^2 + 5x = 8?

Answer 1

3x^2 + 5x - 8 = 0

Use quadratic formula.

x = -b [+/- sqrt (b^2-4ac)]/2
= -5 +/- sqrt [(25 - 4(3)(-8)]/2
= -5 +/- sqrt [(25 + 96)]/2
=-5 +/- 11/2

The positive root is therefore 3.

Answer 2

The first thing you need to do is to subtract 8 from both sides of the equation. This gives you:

3x^2+5x-8 = 0

Now, you need to factor. The trick here is to figure out, which factors of -8, when one of them is multiplied by 3, and the other by 1 will yield +5. (This is the cross product term.)

It turns out that +8 and -1 will do the trick. What you get is the following:

(3x+8)(x-1) = 0

Now, set the x-1 term to 0, and you get:

x-1 = 0 or
x=1

The other root will be negative if you use the same procedure. So, you have your answer.

Answer 3

3x^2 + 5x - 8 = 0

(3x + 8)(x - 1) = 0

(3x +8) = 0 or (x - 1) = 0

x= -(8/3) or x = 1 are the possible roots

Answer 4

Put the equation into standard form:

3x^2 + 5x - 8 = 0

Now you can use the quadratic formula

Answer 5

3x² + 5x - 8 = 0
x = [- 5 ± √121] / 6
x = [- 5 ± 11] / 6
x = 6 / 6 , x = - 16 / 6
Positive root is x = 1

Answer 6

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