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Maths problem

Simultaneous equations

How do you do
2x-3y = 14
4x +2y = -7
Thanks


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Reply 1
Avatar for miikeey97
miikeey97
OP
Simultaneous equations

How do you do
2x-3y = 14
4x +2y = -7
Thanks


Posted from TSR Mobile
Double the first equation and subtract it from the second.
Don't create multiple threads.
Reply 4
Avatar for Robbie242
Robbie242
Original post by miikeey97
Simultaneous equations

How do you do
2x-3y = 14
4x +2y = -7
Thanks


Posted from TSR Mobile
Lets call equation 1 2x-3y=14 and equation 2 4x+2y=-7 Multiply equation (1) by 2 to get 4x-6y=28 and Multiply equation (2) by 3 to get 12x+6y=-21 add the equations together to eliminate y and solve for x.
Reply 5
Avatar for miikeey97
miikeey97
OP
But as the signs are different shouldn't you add them together?


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Reply 6
Avatar for miikeey97
miikeey97
OP
Thanks. I got x = 0.4375. Is this correct or have I gone wrong?


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Original post by miikeey97
But as the signs are different shouldn't you add them together?


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The signs are not different (for the x coefficients we are interested in anyway).
Reply 8
Avatar for Robbie242
Robbie242
Original post by miikeey97
Thanks. I got x = 0.4375. Is this correct or have I gone wrong?


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Should be, I worked it out to 16x=7 x=0.4375 or in other worlds 7/16 if you don't have a calc for the exam.
Reply 9
Avatar for miikeey97
miikeey97
OP
What did you get the answer to be?
Thanks


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Reply 10
Avatar for miikeey97
miikeey97
OP
Cheers, Would y be 4.37 then? :smile:


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Reply 11
Avatar for Robbie242
Robbie242
Original post by miikeey97
Cheers, Would y be 4.37 then? :smile:


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nope it ends up 4(7/16)+2y=-7 7/4+2y=-7 minus 7/4 to get 2y= -35/4 divide by 2 to get y=-35/8 which is -4.375 so you were just an ounce of in terms of the negative sign and lacking 1 decimal.
Original post by miikeey97
What did you get the answer to be?
Thanks


Posted from TSR Mobile


The real question is, what did YOU get the answers to be and we'll tell you if they're correct :smile:
Reply 13
Avatar for sihem
sihem
:confused:
may be y=1.16
Why should we not write multiple threads?


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Original post by domsomething97
Why should we not write multiple threads?


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Spamming clogs up the Forum.

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