I have the co ordinates A (-2 , -2) and B (3 , 1) and I have come up with the slope of my line being -1 using the formula m=y_{2}-y_{1}/x_{2}-x_{1}. Is this correct it feels wrong?

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- Apr 24th 2013, 04:25 AMalexpasty2013Is the slope of my line wrong?
I have the co ordinates A (-2 , -2) and B (3 , 1) and I have come up with the slope of my line being -1 using the formula m=y

_{2}-y_{1}/x_{2}-x_{1}. Is this correct it feels wrong? - Apr 24th 2013, 04:31 AMsa-ri-ga-maRe: Is the slope of my line wrong?
It is wrong. Substitute the values with proper sign.

- Apr 24th 2013, 04:35 AMemakarovRe: Is the slope of my line wrong?
You forgot that you are subtracting negative numbers. Recall that x - (-y) = x + y.

Also, the formula for slope is (y_{2}- y_{1}) / (x_{2}- x_{1}). There is a big difference between this and y_{2}- (y_{1}/ x_{2}) - x_{1}. - Apr 24th 2013, 05:27 AMalexpasty2013Re: Is the slope of my line wrong?
so I have come up with -3/5 now - is this right?

- Apr 24th 2013, 05:37 AMemakarovRe: Is the slope of my line wrong?
- Apr 24th 2013, 06:13 AMalexpasty2013Re: Is the slope of my line wrong?
I had m = 3-(-2)/1-(-2) = -3/5. Point a is (-2,-2) point b is (3,1). I also came up with a midpoint of (-0.5, 0.5) which lies on the line.

- Apr 24th 2013, 06:23 AMemakarovRe: Is the slope of my line wrong?
$\displaystyle 3-(-2)/1-(-2) = 3-\frac{-2}{1}-(-2)=3-(-2)-(-2)=3+2+2=7$, but this has no connection with the original problem.

- Apr 24th 2013, 06:40 AMHallsofIvyRe: Is the slope of my line wrong?
If you

**mean**(3- (-2))/(1-(-2)) then you are not doing what you were told before. 3-(-2)= 3+ 2= 5. 1-(-2)= 1+ 2= 3. The slope is 5/3. No, the midpoint is NOT "(-0.5, 0.5)" nor does that point lie on the line. You were given points (-2 , -2) and B (3 , 1). The midpoint is ((-2+3)/2, (-2+1)/2)= (1/2, -1/2) or (0.5, -0.5). I don't know whether you are confusing x and y, using an incorrect formula, or just doing the arithmetic wrong. - Apr 24th 2013, 06:53 AMemakarovRe: Is the slope of my line wrong?
- Apr 24th 2013, 07:30 AMalexpasty2013Re: Is the slope of my line wrong?
the point (-0.5,0.5 does lie on the line on my graph? Apparently in the middle. For this I used the formula (1/2(x

_{1}+x_{2}) , (1/2(1_{1}+2_{2}).

So I have 3 points, A (-2 , -2), B (3 , 1) and C (6 , 2)

I have calculated slope of line AB = 3/5 with a midpoint at (0.5 , -0.5) and slope of line CB = -1 with a midpoint of (4.5 , -0.5).

All points satisfy a graph with axis scaled at 0 - 0.5 - 1 -1.5 Etc.