Question

Help please!
1/2 x+1/4 y =-4
-2/3 x+1/2 y =7
What is X? and Y?

Answer 1

do you want to do this with the fractions included, or do you want to do a little extra step and turn the fractions into whole numbers where you do not have to deal with the fractions ?

Answer 2

Either or
If its easier keep it in fractions

Answer 3

I think it is easier to turn them to whole numbers. Let me show you how..
1/2x + 1/4y = -4 --- multiply entire equation by common denominator of 4
(4) 1/2x + (4) 1/4y = (4) -4
2x + 4y = -16

now for the other one..
-2/3x + 1/2y = 7 --- multiply by common denominator of 6
(6) -2/3x + (6) 1/2y = (6)7
-4x + 3y = 42

now we have :
2x + 4y = -16
-4x + 3y = 42

now we can either solve by elimination or substitution ...which do you prefer...and do you have any questions so far ?

Answer 4

wait...I caught a mistake...first equation, when multiplied by 4, should be 2x + y = -16

Answer 5

so lets use substitution..
2x + y = -16
y = -2x - 16
now sub -2x - 16 in for y in the other equation.

-4x + 3y = 42
-4x + 3(-2x - 16) = 42
-4x - 6x - 48 = 42
-4x - 6x = 42 + 48
-10x = 90
x = 90/-10
x = -9

y = -2x - 16
y = -2(-9) - 16
y = 18 - 16
y = 2

I might have done something wrong...its not checking correctly...hold on

Answer 6

1/2x + 1/4y = -4
1/2(-9) + 1/4(2) = -4
-9/2 + 2/4 = -4
-18/4 + 2/4 = -4
-16/4 = -4
-4 = -4 (correct)

oh...lol...nevermind...it is correct.
x = -9 and y = 2

Answer 7

http://openstudy.com/study#/updates/54e4c96ee4b0aba126e828fd

Answer 8

Thank so much and thanks for showing me how its done!!

Answer 9

http://openstudy.com/study#/updates/54e4c96ee4b0aba126e828fd