Question

i have trouble factorizing quadratic equations.
eg. x2 -2x -35
i know i have to do (x 5)(x 7)
but i struggle to find whether to put a + or minus

Answer 1

p.s. its not just this question but its fine when its only positivs

Answer 2

$$x^2 -2x -35$$
Factoring pattern for $$x^2 +bx +c$$c negative. Because c is negative the two signs must be opposite, right?

Answer 3

yeah

Answer 4

+ x - = -

Answer 5

So just try both ways and use FOIL.

Answer 6

so for this one its
(x+7)(x-5)

Answer 7

???

Answer 8

am i right?

Answer 9

That would give +2x for the middle term, you want -2x.

Answer 10

+ x - = -
or
- x + = -

Answer 11

(x-7)(x+5)

Answer 12

Correct.

Answer 13

yee tnkx

Answer 14

is there a faster way that does not include trail and error

Answer 15

There is, but you need to develop your skill with using FOIL quickly to help you with many other types of factoring mthods.

Answer 16

foil?

Answer 17

Yes, when multiplying products of the form (ax + b)(cx +d).