# Equation of the line

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• Jan 25th 2010, 04:38 AM
Mist
Equation of the line
How do you solve this?

The line $y= 4x+8$ meets the y-axis at the point B. Find the equation of the line with gradient 2 that passes through the point B.

Spoiler:
$y=4x+8$
$4x+8=0$
$4x=8$
$x=2$

How'd you get the answer?
totally confused
• Jan 25th 2010, 04:51 AM
Archie Meade
If x=0, then y=0+8=8.
Therefore (0,8) is the y-axis crossing point.

A line with gradient 2, passing through this point is $y=2x+8$

since y=mx+c has gradient m.
The gradient is called "m" as it is the multiplier of x
when the linear equation is expressed in the form y=mx+c.
• Jan 25th 2010, 04:56 AM
Raoh
Quote:

Originally Posted by Mist
How do you solve this?

The line $y= 4x+8$ meets the y-axis at the point B. Find the equation of the line with gradient 2 that passes through the point B.

Spoiler:
$y=4x+8$
$4x+8=0$
$4x=8$
$x=2$

How'd you get the answer?
totally confused

hi
write the equation of a line,
$y=mx+b$,m is the gradient (slope),b is the y-intercept.
$m=2$ and $B=(0,8)$
$y=2x+8$.
• Jan 25th 2010, 05:45 AM
Mist
Thanks