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Trying to help daughter solve this easy one.....?
Need to solve:
(3x-4)(2x+7)
please show steps.
Thanks
10 Answers
- 1 decade agoFavorite Answer
You need to multiply each term to the other
(3x)(2x) + (3x)(7) - (4) (2x) - (4)(7)
6x^2 + 21x - 8x - 28
6x^2 + 13x - 28
Good luck
- jim nLv 41 decade ago
There is something missing from the problem as stated.
Did you mean
(1) Solve (3x-4)(2x+7) = 0
or
(2) Carry out the multiplication (3x-4)(2x+7).
For (1):
(3x-4)(2x+7) = 0
The only way two factors can multiply and give 0 is if one of the two factors is equal to 0.
So either 3x-4 = 0 or 2x+7 = 0.
In case 3x-4 = 0 then we get 3x = 4, and then x = 3/4.
In case 2x+7 = 0 then we get 2x = -7, and then x = -7/2.
Thus there are two possible values for x, 3/4 and -7/2.
For (2):
Using the FOIL method we get:
6x^2 + 21x - 8x - 28,
which simplifies to
6x^2 + 13x - 28.
(NOTE: on the keyboard, we use x^2 to mean x to the 2nd power, or x-squared.)
Maybe one of these will help.
- 1 decade ago
If you are solving for x then you get two answers. You must first break the problem into:
3x-4=0
and
2x+7=0
You then solve for X giving you 4/3 and -7/2 respectively.
It would help to know the context of the question.
Good luck!
- Anonymous1 decade ago
first multiply 3x by 2x, then multiply 3x by 7 and add them.
3x*2x + 3x*7 ---> 6x^2 + 21x
then add to that -4 times 2x, then -4 times 7
6x^2 + 21x - 4*2x - 4*7
6x^2 + 21x - 8x - 28 ---> 6x^2 + 13x - 28
to solve those you "FOIL" (First outside, Inside Last)
in variable form, you solve like this:
if you start with (a+b)(c+d)
then first multiply a by both things in the 2nd set of parenthases (c and d), then add those two products together (because c and d are added together)
so you'll have: ac + ad
then multiply b by both things in the 2nd set of parentheses (c and d), then add those two products to what you already had (ac + ad)
so you'll have ac + ad + bc + bd
make sure that if there's anything that can be made simpler, you do it (e.g. if you end up with x^2 + 4x + 7x +2, then make sure you simplify it to x^2 + 11x + 2)
(you can also research the Distributive Property online, because that's what that's called)
Source(s): through 9th grade math. - How do you think about the answers? You can sign in to vote the answer.
- 1 decade ago
(3x-4)(2x+7)
Use FOIL to get next step (first, outside, inside, last)
6x^2 + 21x - 8x - 28
Next, add like terms
6x^2 + 13x - 28
Next, you want to use the quadratic equation which is:
See : http://mathworld.wolfram.com/images/equations/Quad...
You will use A = 6, B=13, and C= -18
Source(s): Math major in college - Anonymous1 decade ago
3x-4 is -12. 2x+7 is the same as 2x7 which is 14. and the way this is set out is all wrong it should say (3x-4)+(2x7) which is 2. because a negative number plus a positive number means that the negative goes up. eg -4+7=3.
Source(s): My maths teacher - 1 decade ago
FOIL (first, outer, inner, last)
(3x-4)(2x+7)
6x^2 + 21x - 6x -28
F 0 I L
6x^2-13x-28 is the answer! Good luck!
Source(s): Math teacher :) - 1 decade ago
is the qns incomplete?
u wanna solve x?
all i got was
6x(squared) + 21x - 8 x - 21= 6x(squared) +13x -21...