View Full Version : 9th Grade Algebra
emmmay61
Mar 13, 2007, 11:18 AM
Solving for a Specific Variable
Solve for y:... I need to show my work
xy = 6
and
x - 4y/3 = 8
HELP
Capuchin
Mar 13, 2007, 11:31 AM
okay rules for this, you must do to the left side, what you do to the right side.
So on the first one, you can divide both sides by x, and you get an equation of the form y= which is what you want.
Now bearing my rule in mind, you work out the answer of the first one (doing what I said), then have a go at the second one.
asterisk_man
Mar 13, 2007, 11:40 AM
the basic idea is that you need to invert every operation so that you just have y on the left.
multiplication and division are inverses
addition and subtraction are inverses
if you've got one you need to apply the other.
remember that x-x=0 and x/x=1
for example:
solve for y
2x+y/7=2
first remove the 2x by subtracting 2x from both sides
2x+y/7-2x=2-2x
the 2x and the -2x on the left cancel to be +0 which can be removed since it contributes nothing
y/7=2-2x
now remove the 7 by multiplying both sides by 7
7*y/7=7*(2-2x)
the 7 and 1/7 combine to be 1 which can be removed because 1*y=y
so now you've got
y=7*(2-2x)
there's one example. Give us what you've gotten so far and we can help you from there.
chancelord
Jun 21, 2008, 04:47 PM
x-4y/3 = 8 first you start by passing the 3 to the other side multiplying it by 8
x-4y= 8.3
x-4y= 24 then, you pass the 4 to the other side by dividing it in 24
x-y= 24/4
x-y= 6 now you must subtract x to 6
-y= 6-x then after this you must divide every ingle term in the equation by -1 that is multiplying by y,
and you got y= -6+x, which is the final answer
mnjkr123
Jun 23, 2008, 09:58 AM
Solve for y:... I need to show my work
xy = 6
and
x - 4y/3 = 8
From xy=6 => x = 6/y
Substitute the value of x in the 2nd equation
6/y-4y/3 =8
Now Multiply by y both on the left and right side
=> 6 - 4 y**2/3 = 8y
=> 4 y**2/3 + 8y - 6 =0
So, now this is quadratic equation
Multiply again by 3 both on the left and right side of "=" sign
=> 4 y**2 + 24 y - 18 = 0
now divide by 2
=> 2 y**2 + 12 y - 9 = 0
y = (-12 ± sq root (144 + 4*2*9))/2*2
y = (-12 ± 14.7 ) / 4
y = 0.675 or -6.675
=>
from mnjkr123
Mathematics Education, Tutoring and Outsourcing (http://mnjkr123.blogspot.com/)
shaebrown
Jun 11, 2009, 04:09 PM
Xy=6
and
x-4y/3=8
so I divide each sid by x and it left me with y
x-4y/3=8
- -
x x
andrik
May 3, 2010, 04:44 PM
okay rules for this, you must do to the left side, what you do to the right side.
So on the first one, you can divide both sides by x, and you get an equation of the form y= which is what you want.
Now bearing my rule in mind, you work out the answer of the first one (doing what i said), then have a go at the second one.
I am a ninth grader and I need help in algebra
Can you help me
andrik
May 3, 2010, 04:46 PM
m=-6/5 and b=-2
amanda.downing96
Jul 19, 2010, 09:31 AM
:confused:
Solving for a Specific Variable
Solve for y: ... I need to show my work
xy = 6
and
x - 4y/3 = 8
HELP
kristylemere
Sep 23, 2010, 06:23 AM
This internet site has the answer and help with the steps
http://www.tutorvista.com/math/solve-this-equation-3x-4y-8
tovian
Feb 4, 2012, 05:48 PM
y=6/x, 3x/4-24=y
tovian
Feb 4, 2012, 05:51 PM
solve the above equation step by step for me please