Expert: Ahmed Salami - 7/29/2009

Question
In the equation y=mx+c.Finding the gradient and the intercept on the y-axis.why is 2x-3y=18 arranged to y=2/3x-6. But 2x+y=3 becomes y=-2+3 or x+3y=6 becomes y=-1/3+2.Hope you can clear this up for me thanks.

Answer
Hi Dave,
The general equation of a straight line is y = mx + c where m is the gradient and c is the intercept on the y - axis.
For 2x - 3y = 18
2x - 18 = 3y
dividing through by 3
(2/3)x - 18/3 = 3y/3
so,
y = (2/3)x - 6
The others are done in a similar way.
2x + y = 3
y = -2x + 3
And
x + 3y = 6
3y = -x + 6
y = -x/3 + 6/3
y = -x/3 + 2

Regards