Find the values of x and y that solve the following system of equations:
- 8x - 3y = 14
- 3x - 7y = 17
Thanks!
2007-11-21 07:49:48 · 3 answers · asked by shauna s 1 in Science & Mathematics ➔ Mathematics
multiply 1st eqn by 7
multiply 2nd eqn by -3:
-56x -21y = 98
9x +21y = -51
add down:
-47x = 47
x = -1
choose either eqn and put in 1 for x:
-8(-1) - 3y = 14
8 - 3y = 14
-3y = 6
y = -2
-3(-1) - 7y = 17
3 - 7y = 17
-7y = 14
y= -2
the point of intersection is (-1,-2)
2007-11-21 07:57:16 · answer #1 · answered by sayamiam 6 · 0⤊ 0⤋
No trig needed here.
-8x -3y = 14
multiply everything (both sides ) by (-3)
-3( -8x - 3y) = -3(14)
24 x + 9y = -42
set aside for now.
Take the second equation:
-3x -7y = 17
multiply everything by 8 (both sides):
8(-3x -7y) = 8(17)
-24x -56 y = 136
Take the two equation that we've just created, and add them together:
24 x + 9y = -42
-24x -56 y = 136
24x -24x +9y -56y = -42 +136
-47 y = 94
y = 94/(-47) = -2
take any original equation and replace y with -2:
-8x -3(-2) = 14
-8x + 6 = 14
-8x = 8
x = -1
2007-11-21 16:00:17 · answer #2 · answered by Raymond 7 · 0⤊ 0⤋
this isn't trig!!!
systems!!! you can use a graph, substitution, or elimination in this case
multiply the first equation by 7
the seconde equation by -3 and y's will cancel out
then you isolate x and plug back in to find y
then you have your coordinates...
(1,2)
2007-11-21 16:04:21 · answer #3 · answered by Anonymous · 1⤊ 0⤋