{y = 4x + 9
{y = 7x + 8
a. (31 / 3, 1 / 3)
b. (1 / 3, 31 / 3)
c. infinite number of solutions
d. no solution
2007-12-03 00:15:57 · 5 answers · asked by . 1 in Science & Mathematics ➔ Mathematics
subsitute one equation with the other, since both have y.
so, 4x + 9 = 7x + 8
4x+1=7x
3x=1
x=1/3
subsitute again with any equation
y = 4(1/3) + 9
y = 4/3 + 9
y = 4/3 + 27/3
y = 31/3
(1/3, 31/3), so it's letter B.
2007-12-03 00:22:37 · answer #1 · answered by Geommm 2 · 3⤊ 0⤋
y=4x+9
y=7x+8
4x+9=7x+8
9-8=7x-4x
1=3x
x=1/3
y=4(1/3)+9
y=31/3
off course the answer is b.
2007-12-03 08:33:39 · answer #2 · answered by kamjinga 2 · 1⤊ 0⤋
[sol]
since y is equal to both 4x+9 and 7x+8, it means that they are equal to each other....
so, 4x+9=7x+8
solving it, 4x+9-4x=7x+8-4x (to isolate 7x)
9=3x+8
9-8=3x+8-8 (to isolate 3x)
1=3x
1/3=3x/3 (to isolate x)
1/3=x
and then substitute it into any of the equations so...
y=4x+9
y=4(1/3)+9
=4/3+9
=31/3
therefore, your answers are x=1/3, y=31/3
2007-12-03 08:28:53 · answer #3 · answered by theclassbookworm0615 2 · 2⤊ 0⤋
4x + 9 = 7x + 8
3x = 1
x = 1/3
y = 4/3 + 9
y = 31/3
OPTION b
2007-12-03 10:35:17 · answer #4 · answered by Como 7 · 2⤊ 1⤋
4x+9=7x+8
-3x+9=8
-3x=-1
x=1/3
4(1/3)+9
4/3+27/3
y=31/3
The answer is b.
2007-12-03 08:49:53 · answer #5 · answered by Anonymous · 0⤊ 0⤋