Plese help with factoring?

Question

This is supposed to be easy, but I can't seem to figure it out.

x^2+3x-20

Thanks

Answer 1

Factor the expression using the Quadratic Formula which, is...
x = [-b +/- V`b^2 - 4ac] / 2a

First: identify 3 terms...a = 1; b = 3; c = - 20
SEc: substitute the terms with the corresponding variables.

x = [- 3 +/- V`3^2 - 4(1)(-20)] / 2(1)

x = [- 3 +/- V`3*3 - 4(1)(-20)] / 2

x = [- 3 +/- V`9 - 4(1)(-20)] / 2

x = [- 3 +/- V`9 - 4(-20)] / 2

x = [- 3 +/- V`9 + 80] / 2

x = [- 3 +/- V`89] / 2

Third: you will always have two solutions.

x = [- 3 + V`89] / 2 and [- 3 - V`89] / 2

Answer 2

You need to find two numbers that add up to 3 but multiply out to -20.
Here are the options that multiply out to -20
-20 and 1
-10 and 2
-5 and 4
-4 and 5
-2 and 10
-1 and 20
None of these pairs add up to 3, so it cannot be factored.

Check: Look at the discriminant of the quadratic formula. If it's not a perfect square, the equation cannot be factored. b^2-4ac = 9-4(1)(-20) = 89 which is not a perfect square!

Answer 3

i dont think its factorable

becuase the only factors of 20 are:

4*5=20
10*2=20
20*1=20

and none of them add up to get the middle term which is 3

Answer 4

x^2+3x-20
x = [-3 +/- sqrt(3^2-4(1)(-20)]/(2*1)
x = [-3 +/- sqrt(89)]/2
x = -1.5 +/- 4.717
x = 3.217 and -6.217

Answer 5

(x - {–3 + (89^0.5)}/2) * (x - {–3 - (89^0.5)}/2)

of, if one prefers:

(x + 1.5 - (89^0.5)/2) * (x + 1.5 + (89^0.5)/2)

or, in decimal form:

(x - 3.21699) * (x + 6.21699)

Answer 6

This is unfactorable