This is one is so confusing to me because of how it's written out!! This is how I THINK I'm supposed to go about this.
y=0-9x *Doesn't make sense to me*
-4x+(0-9x)=21
-4x+0-9x=21
-13x-9=21 see now I'm totally out of it! any help pleaaase?
2007-05-20 14:02:05 · 7 answers · asked by Doug C 1 in Science & Mathematics ➔ Mathematics
So the answer is (-4/7,12/7) as in fractions?
2007-05-20 14:16:04 · update #1
-4x+4x+y=4+4x (add 4x to both sides of the second equation)
y=4+4x (-4x and +4x cancel each other out)
9x +3(4+4x)=0 (substitute 4+4x for y in the first equation)
9x + 12 + 12x = 0
21x + 12 = 0 (9x + 12x = 21x)
21x = -12 (subtract 12 from both sides)
x=-12/21 (divide both sides of the equation by 21)
x=-4/7 (reduce the fraction by dividing both the numerator and the denominator by 3)
y=4+4x
y=4+4*-4/7 (substitute -4/7 for x)
y=4-16/7 (multiply 4*4)
y=28/7-16/7 (make 4 into 28/7)
y=12/7 (subtract 16 from 28)
Yes, as an ordered pair the answer would be (-4/7,12/7)
You're welcome, Doug.
2007-05-20 14:19:30 · answer #1 · answered by David C 3 · 0⤊ 0⤋
Question 1 y = 1 - x x² - (1 - x) = 1 x² + x - 1 = 1 x² + x - 2 = 0 (x + 2)(x - 1) = 0 x = - 2 , x = 1 y = 3 , y = 0 (- 2 , 3) , (1 , 0) Question 2 y = 4x / 3 x² + 16x² / 9 = 25 9x² + 16x² = 225 25x² = 225 x² = 9 x = 3 , x = - 3 y = 4 , y = - 4 (3,4) (- 3 , - 4)
2016-05-22 12:06:31 · answer #2 · answered by maribeth 3 · 0⤊ 0⤋
Firstly, if you want to use the first equation, then you subtract 9x, and divide by three on both sides, so,
3y=-9x or y=-3x
Now, you can substitute into the second equation:
-4x-3x = 4 or
-7x=4 or
x=-4/7
Now substitute this back into the second equation and you get:
-4(-4/7) + y = 4
16/7 + y = 4
or y=12/7
2007-05-20 14:16:30 · answer #3 · answered by Anonymous · 1⤊ 0⤋
The first step in solving this would be to solve for either x or y in one of the equations.
I would solve for y in the first one (since that's easier and doesn't leave you with annoying fractions), which would get you y=-3x.
You would then replace the y in the second equation with -3x, or -4x+(-3x)=4, which is -7x=4, or x=-4/7.
Going back and replacing -4/7 in for x in either of the equations would get you 12/7 for y.
2007-05-20 14:07:59 · answer #4 · answered by RandomNormality 3 · 1⤊ 0⤋
-4x + y = 4; y = 4x + 4
9x + 3y = 0
9x + 3(4x + 4) = 0
9x + 12x + 12 = 0
21x = -12
x = -12/21 = -4/7
y = 4x + 4
y = 4(-4/7) + 4 = -16/7 + 4 = -16/7 + 28/7 =
12/7
2007-05-20 14:05:58 · answer #5 · answered by richardwptljc 6 · 1⤊ 0⤋
You solved for y wrong. y =/= 0-9x, y = 0-3x.
2007-05-20 14:11:29 · answer #6 · answered by Uryx 3 · 0⤊ 1⤋
y=4x+4
9x+3(4x+4)=0
9x+12x+12=0
21x+12=0
21x+12-12=0-12
21x=-12
21x/21=-12/21
x=-12/21=-4/7
-4(-4/7)+y=4
16/7+y=4
16/7-16/7+y=4-16/7
y=12/7
2007-05-20 14:19:29 · answer #7 · answered by Dave aka Spider Monkey 7 · 1⤊ 0⤋