# Simultaneous equation problem

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• August 19th 2012, 04:21 PM
william24
Simultaneous equation problem
Use the method of elimination to solve the following simultaneous equations.
http://www.eso.org/sci/software/esom...vola/img49.gif-5p+q/2=-3/2
2p+3q/2=4

What are the following steps?
• August 19th 2012, 04:34 PM
pickslides
Re: Simultaneous equation problem
To eliminate p, multiply the first equation by two, the second by 5 and add the results.
• August 19th 2012, 07:25 PM
william24
Re: Simultaneous equation problem
-5p+q/2=-3/2......(1)
2p+3q/2=4......(2)

(1)x2
(-5p)x2+(q/2)x2=(-3/2)x2
-10p+q=-3

(2)x5
(2p)x5+(3q/2)x5=(4)x5
10p+15q/2=20

(-10p+q)+(10p+15q/2)=-3+20
16q/2=17
??
• August 19th 2012, 07:32 PM
pickslides
Re: Simultaneous equation problem
$\left( -10p+q \right) + \left( 10p+\frac{15q}{2} \right)= \left( -10p+\frac{2q}{2} \right) + \left( 10p+\frac{15q}{2} \right) = \frac{17q}{2}$

Then

$\frac{17q}{2} = 17 \implies q=2$
• August 19th 2012, 07:40 PM
william24
Re: Simultaneous equation problem
Thx for ur help.
My answer booklet's answer is q=-2 and p=1
After I follow ur method to do, I also got the q=2 answer.
Is there are somethin' wrong??