Question

Help with factoring? @johnweldon1993

Answer 1

Some steps to rewrite the expression x^3 - 9x + x^2 - 9 as a product of three factors are shown below:

Step 1: x^3 - 9x + x^2 - 9
Step 2: x^3 + x^2 - 9x - 9
Step 3: x^2(x + 1) - 9(x + 1)

Which of the following best shows the next two steps to rewrite the expression?

Step 4: (x^2 + 9)(x + 1); Step 5: (x + 3)(x + 3)(x + 1)

Step 4: (x^2 - 9)(x + 1); Step 5: (x + 3)(x + 3)(x + 1)

Step 4: (x^2 + 9)(x + 1); Step 5: (x - 3)(x + 3)(x + 1)

Step 4: (x^2 - 9)(x + 1); Step 5: (x - 3)(x + 3)(x + 1)

Answer 2

\[\large \color \red{x^2}(x + 1) \color \red{- 9}(x + 1)\]

write these in 1 parenthesis...and write the (x + 1) in the other

\[\large (x^2 - 9)(x + 1)\]

Step 5 would be simplifying the left parenthesis..

Use the fact that

\[\large a^2 - b^2 = (a + b)(a - b)\]

so

\[\large (x + 3)(x - 3)(x + 1)\]

Answer 3

So... the +1 just disappears?

Answer 4

What do you mean....oh what the fact that there are 2 (x + 1) ?

no you just write 1 of those

Answer 5

oic... so thats how u factor?

Answer 6

mmhmm....this is called "grouping" and is an easy way to tackle factoring when you have a 3rd degree polynomial like this

Answer 7

Oh ok... Thanks c:

Answer 8

Well of course :)