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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE General & Further Mathematics => Topic started by: clinton_09 on November 01, 2008, 04:22:09 pm

Title: Transposing help
Post by: clinton_09 on November 01, 2008, 04:22:09 pm: hi im terrible at transposing, i was hoping someone could show me the methods of transposing that first equation. Thanks :) :)

For the pair of simulatenous equations

4x= 7-y

5x+7y=3

the solutions are:
Title: Re: Transposing help
Post by: Flaming_Arrow on November 01, 2008, 04:39:07 pm: $1. 4x= 7-y$

$2. 5x+7y=3$

$4x - 7 = -y$

$\implies y = -4x + 7$

so we can sub that into the 2nd equation

$5x+7(-4x + 7)=3$

$5x - 28x + 49 = 3$

$-23x + 49 = 3$

$-23x = - 46$

$\boxed {x = 2}$

and we can sub x into any equation to get to value of y

$4(2)= 7-y$

$\boxed {y = -1}$

or

$5(2)+7y=3$

$10+7y=3$

$7y=3-10$

$7y=-7$

$\boxed { y = -1}$
Title: Re: Transposing help
Post by: RD on November 01, 2008, 04:42:01 pm: Wow.. a year 11 teaching a year 12, who would've thought!!

(Btw, I'm as bad as you on transposing clinton :P)
Title: Re: Transposing help
Post by: clinton_09 on November 01, 2008, 04:56:25 pm: thanks chath :)