Question

expand 2x^2+3x+1

Answer 1

Already expanded. Do you want to factor?

Answer 2

yes

Answer 3

What have you tried till now?

Answer 4

(2x-1) (3x+1)

Answer 5

the factors of the last term need to add up to the middle term.

Answer 6

You know that the first factors are not 2x and 3x since 2x*3x = 6x^2

Answer 7

(2x+1) (x+2)

Answer 8

The last terms, 1 and 2, when multiplied is 1*2 which equals 2. You are looking for +1

Answer 9

Remember that when you are factoring you can always check your answer by expanding.

With (2x +1)(x+2) you can multiply it out using FOIL (First, Outside, Inside, Last).

First: 2x times x = 2x^2, so far so good.
Outside: 2x times 2 = 4x
Inside: 1 times x = x
Last: 1 times 2 = 2.

So, you end up with 2x^2 +4x+x+2 = 2x^2 +5x+2, not correct.

Answer 10

I would use the quadratic for this one since it is hard to figure out the roots for this by factoring.

Answer 11

lol at least for me

Answer 12

I disagree @Nameless, factoring is the way to go here.

Answer 13

show me the way :)

Answer 14

(2x+1)(x+1) = 2x^2+2x+x+1 = 2x^2+3x+1

Answer 15

You know that the first terms are 2x and x since you need 2x^2
You know that the last terms are either +1,+1 or -1,-1 since you need +1. Trial and error gives you +1,+1

Answer 16

teic85 is right

Answer 17

yep :) i was only saying the quadratic works better for me.

Answer 18

agree.

Answer 19

The quadratic works best because it will solve any quadratic equation. It's a failsafe. But, students need to know how to factor as well.

Answer 20

thanks teic

Answer 21

You're welcome! :)

Answer 22

The best way to master these is to practice. You'll start to see patterns and begin to factor in your head.