15c^2-7cd-2d^2

Question

15c^2-7cd-2d^2

calculusfunctions · Answer

$$15c ^{2}-7cd -2d ^{2}$$You want to factor this expression correct?

anonymous · Answer

yes

calculusfunctions · Answer

So do you need help with factoring in general or just this particular question?

anonymous · Answer

when there is two variables i get stuck... 
do i have to the factor of seven which adds to two?

calculusfunctions · Answer

Factoring with two variables is no different, except each binomial factor now also enads with a variable.

Example:
Factor the following

i).  x² - 2x -8 

  = (x - 4)(x + 2)


ii).  x² - 2xy - 8y²

   = (x - 4y)(x + 2y)



Do you see?

calculusfunctions · Answer

*ends

calculusfunctions · Answer

Now you do your question and if you want, I will check it.

anonymous · Answer

what do i do with "15"?
im stuck ok so (15c-?d)(c+?d)   ?????

calculusfunctions · Answer

Example:
Factor  3x² - 2xy - 5y²

Step 1:  Find two integers with a product of  (3)(-5)  or  -15  and a sum of  -2. The two integers would be  +3  and  -5.

Decomposition method:  (decompose the middle term in terms of the two integers)

  3x² + 3xy - 5xy - 5y²   (now group and factor the first two terms and then the last two)

= 3x(x + y) - 5y(x + y)  (now we have  x + y  as a common factor)

= (x + y)(3x - 5y)


Do you understand?  If you want I can also teach you other methods besides decomposition.