Elimination using Multiplication. (In word-problem format.)

[morraco]

I get the format of this:

Two times a number plus three times another number equals 13. The sum of the two numbers is 7. What are the numbers?

I know it should be:

2x+3y=13
x+y=7

But when I try to figure it out... I can't get a proper answer! Call me a moron if you wish, I most likely am, but my brain's about ready to implode.

 

[TchrQbic]

Re: Elimination using Multiplication. (In word-problem forma

I get the format of this:

Two times a number plus three times another number equals 13. The sum of the two numbers is 7. What are the numbers?

I know it should be:

2x+3y=13
x+y=7

But when I try to figure it out... I can't get a proper answer! Call me a moron if you wish, I most likely am, but my brain's about ready to implode.

You can use either substitution (by rearranging the second equation and subbing into the first one) or by eliminating one of the variables using multiplication and addition. Which method have you tried? If you show your work we can see where an error is occurring and help you.

 

[Straight edge man]

yes that would def. help... but just to give you a little hint on the problem... since you know you have the two equations multiply the bottom equation by a (-) number (cant tell you hte number) then use elimination method..........

 

[Denis]

Re: Elimination using Multiplication. (In word-problem forma

I get the format of this:
Two times a number plus three times another number equals 13. The sum of the two numbers is 7. What are the numbers?
I know it should be:
2x+3y=13
x+y=7
But when I try to figure it out... I can't get a proper answer! Call me a moron if you wish, I most likely am, but my brain's about ready to implode.

2x + 3y = 13 [1]
x + y = 7 : y = 7 - x [2]

Substitute [2] in [1]:
2x + 3(7 - x) = 13
2x + 21 - 3x = 13
x = 8

Substitute in [1] or [2] to get y = -1

What exactly was your problem?