Question

If A ( 3, 5) and B (1, 4) lie on the graph of the line mx+cy = 7, find m and c​

Answer 1

m = -1, c = 2

Explanation:

if A ( 3, 5) and B (1, 4) lie on the graph of the line mx + cy = 7, then their coordinates satisfy the equation of the line:

A:
`3m+5c=7`

B:
`m+4c=7`

From the second equation:

`m=7-4c`

Substitute it into the first equation:

`3(7-4c)+5c=7\\ \\21-12c+5c=7\\ \\-12c+5c=7-21\\ \\-7c=-14\\ \\c=2\\ \\m=7-4\cdot 2=7-8=-1`