razrulz wrote:

Avis wrote:

y-intercept is the value of b.

I think what zoelef has is the x-intercept.

but how u got b ==> 2/5 ?? i dont understand...

You must know the formula in such cases...

We have (1;1) (-4;-2) on the coordinate plane...

the basic equation here is y=mx+b (where m is the slope of the line, x is the x intercept of the line and b is y intercept of the line)

Now first of all we need a slope of the line:

The slope of the line is m=change in y/change in x or (y1-y2)/(x1-x2)

Plug in the numbers... m=(-2-1)/(-4-1)=3/5

Now to find the equation use the same formula which we used in order to find the slope....

m=(y1-y)/(x1-x)....... m(x1-x)=y1-y once again plug in the values for x1 and y1 and m....

3/5(-4-x)=-2-y

-12/5-3/5x=-2-y

-y=2-12/5-3/5x..... 2-12/5 equals -2/5

-y=-2/5-3/5x

y=3/5x+2/5

now we remember the formula y=mx+b where b denotes y intercept, this means y intercept is 2/5.....

If we were also asked to calculate the x intercept we would give y the value of 0 and solve the equation....

3/5x+2/5=0

3/5x=-2/5

x=-2/3, this line croses x axis at -2/3.....