find the values for x and y
9x+5y=24
-5x-2y=-11
2007-02-20 18:06:32 · 4 answers · asked by chichidb18 2 in Science & Mathematics ➔ Mathematics
If you look at the equations, decide what you want to eliminate first. If you decide to eliminate the x term you need to make them either the same or opposite numbers. One way that works, but sometimes gives numbers that are larger than needed is to multiply the first equation by the coefficient(number with the x term) of the x term in the second equation and multiply the second equation by the coefficient of the first equation.
Sounds confusing, but for this one, multiply the first equation by -5 and the second equation by 9
You get
-45x - 25y = -120
-45x-18y = -99
Subtract and get
-7y = -21
y = 3
Now that you have a y number go back to either original equation and put it in to find the x number
9x + 5(3) = 24
9x + 15 = 24
9x = 9
x = 1
The answer is (1,3)
2007-02-20 18:20:53 · answer #1 · answered by lizzie 3 · 0⤊ 0⤋
2(9x+5y)=48
5(5x+2y)=55
18x+10y=48
-25x-10y=-55
add
-7x=-7
x=1
18+10y=48
10y=30
y=3
2007-02-20 18:23:45 · answer #2 · answered by Anonymous · 0⤊ 0⤋
I'm doing this same stuff in my math class and i hate it. I don't get how to do these so i usually just keep guessing numbers for x and y untill it equals what the answer is supposed to be.
2007-02-20 18:11:25 · answer #3 · answered by JaggedLittlePill 4 · 0⤊ 0⤋
multiply the first by 2
the second by 5
then add
18x+10y=48
-25x-10y=55
------------------------------
-7x=-7
x=1
2007-02-20 18:13:13 · answer #4 · answered by iyiogrenci 6 · 0⤊ 0⤋