Question:
How do I solve 9p=2q-6 3p-q=12 using substitution?
anonymous
2011-12-23 21:51:01 UTC
The problem is
9p=2q-6
3p-q=12

I dont know how to do substitution please help and list steps and details
thank you
Thirteen answers:
llaffer
2011-12-23 21:57:25 UTC
Substitution is the method you will most likely use when solving this type of problem.



First, you have to take one of the equations and solve it for one variable in terms of the other. It doesn't matter which one you use, you'll get the same answer. So go with what may be the easiest.



solving for the q in the 2nd equation seems to be the easier approach, so I'll do that:



3p - q = 12

-q = 12 - 3p

q = -12 + 3p



Now we have an expression for q. Now we substitute the value of (-12 + 3p) for q in the other equation, then we can solve for p:



9p = 2q - 6

9p = 2(-12 + 3p) - 6

9p = -24 + 6p - 6

3p = -30

p = -10



Now that we have a value for p, substitute that into either of the two equations and solve for q.



q = -12 + 3p

q = -12 + 3(-10)

q = -12 - 30

q = -42



The answer to the set of equations is:



p = -10

q = -42
bobbyjimthefirst
2011-12-23 21:57:05 UTC
Hi C,



Let:



[1] 9p=2q-6.

[2] 3p-q=12.



Rearrange [2] by adding q:



3p = 12 + q.



Then subtract 12:



3p - 12 = q.



Put this version of q into [1]:



9p = 2q - 6 = 2 * (3p - 12) - 6.



Expand the brackets:



9p = 6p - 24 - 6.



Subtract 6p:



3p = - 24 - 6 = - 30.



Divide by three:



p = - 10.



Put this version of p into [2]:



3p - q = 12.



3 * (- 10) - q = 12.



Multiply out:



-30 - q = 12.



Add 30:



-q = 42.



Multiply by -1:



q = - 42.



Solution:



p = - 10.

q = - 42.
avip
2011-12-23 23:19:27 UTC
3p-q=12

=> q= 3p -12

put p = 3p -12, to get

=> 9p = 2(-12+3p)-6

=> 9p = -24+6p-6

=> 3p=-24-6

=> p=-10

put p = -10 in 1st eqn, to get

=> 3(-10) - q = 12

=> -30-q = 12

= > -q= 42

=> q= - 42

Answer
?
2011-12-23 22:02:41 UTC
To do substitution, solve one of your equations for one variable, then "substitute" that into the other equation.



Looking at your two equations, the only variable with no coefficient is the -q in the second one, so solve that for q.



3p - q = 12

-q = -3p + 12

q = 3p - 12



Now you know what q equals, so "substitute" that into the first equation & solve for the other variable



9p = 2q - 6

9p = 2(3p - 12) - 6

9p = 6p - 24 - 6

9p - 6p = -24 - 6

3p = -30

p = -30/3 = -10



q = 3p - 12 = 3*(-10) - 12

q = -42



q = -48



p = -12, q = -48
James
2011-12-23 22:26:30 UTC
9p=2q-6 equation (1)

3p-q=12 equ. (2)

then 4rm equ. 1 make p d subject of formular P=2q-6 all over 9.

In equ. 2 subtitute p=2q-6allover9 into equ. 2

dat is 3p-q=12,so put 3(2q-6allova9)-q=12,get q=-42 work t vry wel and get ur p as -10 Goodluck
Nigel
2011-12-23 22:23:18 UTC
9p=2q-6

3p-q=12



3p-q+q=12+q

3p-12=q+12-12

3p-12=q

sub 3p-12 for q

9p=2(3p-12)-6

(9p=6p-30)/3

3p=2p-10

now use common sense to find p, if 2p-10=3p then 1p=-10 because 2(-10)-10=3(-10)

-90=2q-6

-84=2q

-42=q

Answers:



p=-10

q=-42
?
2011-12-23 21:54:50 UTC
9p=2q-6



3p-q=12

add q to both sides



3p=q+12

subtract 12 from both sides



q=3p-12



substitute 3p-12 for q in 9p=2q-6

9p=2(3p-12)-6

distribute the 2



9p=6p-24-6

9p=6p-30

subtract 6p from both sides

3p=-30

divide by 3



p=-10
i_einstein
2011-12-23 22:03:43 UTC
given

9p=2q-6

3p-q=12

to solve using substitution

9p=2q-6

9p+6=2q

q=(9p+6)/2

Sub it in 3p-q=12



3p-(9p+6)/2=12

6p-9p-6=24

-3p=30

p=-10

q=(9p+6)/2

q=(-9*10+6)/2

q=-84/2

q=-42



Solution p=-10 q=-42





Hope it helps
;P
2011-12-23 21:56:10 UTC
You have to solve for one value and then plug it in .



3p-q=12

-q=12-3p

q=-12+3p



9p=2(-12+3p)-6

9p=-24+6p-6

3p=-24-6

p=-10



3(-10)-q=12

-30-q=12

-q=42

q=-42
declue
2016-11-30 06:53:48 UTC
a million.) 3(4x+a million a million/2y + 2) - 5(2x + a million a million/2y)=0 2(3x - 3y + a million) - 2(2x - 2 a million/2y+4)=0 12x + 4y + 6 - 10x - 7y = 0 2x - 3y + 6 = 0 6x - 6y + 2 - 4x + 5y - 8 = 0 2x - y - 6 = 0 convert one equation to appear like, x= or y= 2x-y-6=0 -y = -2x+6 y = 2x-6 making use of the 2d equation, enter y to clean up for x 2x-3y+6=0 2x - 3(2x-6) + 6=0 2x-6x+18+6=0 -4x+24=0 -4x=-24 x = 6 making use of the unique equation, enter x to clean up for y 2x-y-6=0 2(6)-y-6=0 12-y-6=0 6-y=0 -y=-6 y = 6 x = 6, y = 6 to envision your answer enter the two x and y into between the equations, and it might come out.
Alfonso S
2011-12-23 21:55:53 UTC
solve for q in the second equation, then substitute that in the first equation.



q = 3p-12

9p=2(3p-12)-6

9p=6p-24-6

9p=6p-30

3p=-30

p=-10

then

q=-42..
Como
2011-12-24 00:13:12 UTC
q = 3p - 12



9p = 6p - 24 - 6

3p = - 30

p = - 10



q = - 30 - 12

q = - 42



p = -10 , q = - 42
MaxxC
2011-12-23 21:55:17 UTC
i cant work it right now because of my lack of paper but isolate the "p" or "q" and then use simple algebra to continue on with the problem


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