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simultaneous equations

when doing simultaneous in 3 variables is it okay to do this?

10 + 6g + 2f +c = 0

2 + 2g + 2f + c = 0

can I get rid of both f and c? and then solve for g?
Reply 1
Avatar for Star-girl
Star-girl
12
Original post by madfish
when doing simultaneous in 3 variables is it okay to do this?

10 + 6g + 2f +c = 0

2 + 2g + 2f + c = 0

can I get rid of both f and c? and then solve for g?


Consider what happens when you subtract one equation from the other.
Reply 2
Avatar for madfish
madfish
OP
Original post by Star-girl
Consider what happens when you subtract one equation from the other.

yes I know, f and c get elminated

is this okay even though there are 3 variables and not 2?
Yea, you can subtract the 2f and the c.

Also if they're both equal to the same thing (0 in this case), then they are equal to each other, so you can make it into one simple equation.
Reply 4
Avatar for tory88
tory88
18
Original post by madfish
when doing simultaneous in 3 variables is it okay to do this?

10 + 6g + 2f +c = 0

2 + 2g + 2f + c = 0

can I get rid of both f and c? and then solve for g?


Yes, it's fine. And will get you a value for g. Then just sub this in and solve as usual.
Reply 5
Avatar for Star-girl
Star-girl
12
Original post by madfish
yes I know, f and c get elminated

is this okay even though there are 3 variables and not 2?


Yes. It doesn't matter how many variables there are in the equation, if some cancel then that's that.

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