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# 30=r24+s42 find r and s watch

1. thought I'd be able to use substitution but struggling.
2. What is this? Algebra? There must be more to the question.
You've got 1 equation and 2 variables so there's an infinite number of answers.
3. (Original post by Trackstar)
thought I'd be able to use substitution but struggling.
4. (Original post by Trackstar)
thought I'd be able to use substitution but struggling.
Do you mean

30 = 24 r + 42 s where r and s are whole numbers?

If so, for numbers this size, trial and error is probably the quickest solution, although you might as well divide through by 6 so you're solving

5 = 4 r + 7 s.

It's also worth noting that if you find a solution to

1 = 4 r + 7 s,

you can just multiply r and s by 5 to get a solution to 5 = 4r + 7s.

Edit: for a non-trial-and-error method, you could look up the Extended Euclidean Algorithm, but I feel this will probably be overkill...
5. (Original post by DFranklin)
Do you mean

30 = 24 r + 42 s where r and s are whole numbers?

If so, for numbers this size, trial and error is probably the quickest solution, although you might as well divide through by 6 so you're solving

5 = 4 r + 7 s.

It's also worth noting that if you find a solution to

1 = 4 r + 7 s,

you can just multiply r and s by 5 to get a solution to 5 = 4r + 7s.

Edit: for a non-trial-and-error method, you could look up the Extended Euclidean Algorithm, but I feel this will probably be overkill...
no, this just confirmed my method was wrong. the question is. b=24, c=42 find r,s such that q=rb+sc for,

q=30
q=32
6. (Original post by Trackstar)
no, this just confirmed my method was wrong. the question is. b=24, c=42 find r,s such that q=rb+sc for,

q=30
q=32
You still have 2 variables and only 1 equation. Doesn't it say anything else about r and s?
7. Can u show us the full question？
8. (Original post by Trackstar)
no, this just confirmed my method was wrong. the question is. b=24, c=42 find r,s such that q=rb+sc for,

q=30
q=32
You really need to clarify whether r and s are supposed to be integers. The form of question strongly indicates that they are, however:

Spoiler:
Show
It's not possible to find integer r,s s.t. 24 r + 42 s = 32.
9. (Original post by DFranklin)
You really need to clarify whether r and s are supposed to be integers. The form of question strongly indicates that they are, however:

Spoiler:
Show

It's not possible to find integer r,s s.t. 24 r + 42 s = 32.
they are sorry, I have done it now.

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