# point of intersection

• Dec 8th 2008, 06:46 PM
heatherblack87
point of intersection
find the point of intersection of the lines: 3x + 4y = -6 and 2x + 5y = -11
• Dec 8th 2008, 06:59 PM
euclid2
Quote:

Originally Posted by heatherblack87
find the point of intersection of the lines: 3x + 4y = -6 and 2x + 5y = -11

3x + 4y = -6
2x + 5y = -11

use elimination multiply the first by -2 and the second by three

(3x + 4y = -6)*-2
(2x + 5y = -11)*3

-6x-8y=12
6x+15y=-33

cancel the x's

-8y=12
15y=-33

7y=-21
y=-21/7
y=-3

now sub to find x
• Dec 8th 2008, 07:36 PM
mr fantastic
Quote:

Originally Posted by euclid2
3x + 4y = -6
2x + 5y = -11

use elimination multiply the first by -2 and the second by three

(3x + 4y = -6)*-2
(2x + 5y = -11)*3

-6x-8y=12
6x+15y=-33

cancel the x's

-8y=12
15y=-33

7y= - 21
y= - 21/7
y= - 3

now sub to find x

Small corrections in red.
• Dec 8th 2008, 07:37 PM
euclid2
Quote:

Originally Posted by mr fantastic
Small corrections in red.

I appreciate that, no wonder when i subed the y value the answer was so chaotic, lol