I am checking a freinds homework and cant remember how to do these.
1.Solve: (5x/4)-(5x/7)=(5/28)
2.Solve for y. x + 3y = 9
2007-10-07 05:53:44 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
1. 5x/4 -5x/7 =5/28
Multiplying both sides by 28
28(5x/4)-28(5x/7)=28*5/28
35x-20x=5
15x=5
x=5/15=1/3
x+3y=9
3y=9-x
y=(9-x)/3
the value of y will depend upon the va;ie of x
If x=0,y=3
If x=3.y=2
ifx=6,y=1
if x=-3 ,y=4 and so on
2007-10-07 06:04:13 · answer #1 · answered by alpha 7 · 0⤊ 0⤋
1.Solve: (5x/4)-(5x/7)=(5/28)
35x/28 -20x/28 = 5/28
15x = 5
x = 1/3
2.Solve for y. x + 3y = 9
3y = 9-x
y = (9-x)/3
2007-10-07 06:01:16 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
1. Find a common denominator:
(35x-20x)/28=5/28
15x/28=5/28
Since the denominators are now equal,
15x=5
x=1/3
2. Just rearrange the equation:
3y=9-x
y=3-x/3
2007-10-07 05:59:46 · answer #3 · answered by Drew C 1 · 0⤊ 0⤋
In the first change so all are over 28 by multiplying top and bottom by 7 then 4
35x/28 - 20x/28 = 5/28
Since the bottoms are the same so must be the tops so solve
35x - 20x = 5
On #2, subtract x from both sides then divide everything by 3
3y = 9 - x
y = 3 - x/3
2007-10-07 05:58:04 · answer #4 · answered by hayharbr 7 · 0⤊ 0⤋