line joining

Prove It

MHF Helper
Aug 2008
12,883
4,999
what is the line joining (-4,1) and (-2,5)
Here you have

\(\displaystyle (x_1, y_1) = (-4, 1)\)

and

\(\displaystyle (x_2, y_2) = (-2, 5)\).



The equation of the line is

\(\displaystyle y - y_1 = m(x - x_1)\), where \(\displaystyle m = \frac{y_2 - y_1}{x_2 - x_1}\).
 
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Feb 2010
5
1
Firstly, you need to find the gradient, in the form

y=mx+c

The formula for gradient is

(y1-y2)/(x1-x2)

so

(5-1)/(-2--4) = 4/2 = 2

So you know that the line is y=2x+c

Now substitute one of the points into the equation

1=2(-4)+c

1=-8+c

so 9 = c

So the equation of the line is

y=2x+9
 
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