Question

2x2+3x-20=0

Answer 1

here is a method that works every time

for

\[ax^2 + bx + c \]

start by multiplying a and c

in your question its 2 and - 20 = -40

so find the factors of -40 that add to 3..... the larger factor is positive...

what did you get..?

Answer 2

or you can wait for someone to give you the answer

Answer 3

The factors are 8 and 5
And since the larger factor must be positive, that means the other is negative so...
8-5

Answer 4

so the you write it as

(ax + factor 1)(ax + factor 2)
------------------------- = 0
a

so

(2x + 8)(2x - 5)
-------------- = 0
2

remove any common factors from the binomials

2(x + 4)(2x - 5)
-------------- = 0
2

you'll see the common factor cancels with the denominator and you have the factored form.

works every time. Provided the quadratic can be factored

then its just a case of solving the bnomials