Solving for a Specific Variable

Solve for y: ... I need to show my work

xy = 6

and

x - 4y/3 = 8


HELP

Capuchin

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

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

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

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

shaebrown

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