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I'm currently having a problem with this

$$2x – 5y = 10$$

I'm supposed to write given equation in slope-intercept form and identify slope. I did that, but I thought the answer was $5$, but it keeps telling me I'm wrong. Then I did it again, and got an answer of $2.5$ but it keeps telling me I'm wrong, so I'm not sure what I'm doing wrong. If anyone could help, that would be great. :-)

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  • $\begingroup$ The answer is 2/5 = 0.4 ? $\endgroup$ – NeilRoy May 2 '15 at 13:27
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    $\begingroup$ Hint. Can you put that equation in the form $y = ...$? $\endgroup$ – Ethan Bolker May 2 '15 at 13:27
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    $\begingroup$ @neilroy That's what I was getting, but I must've forgot the 0.4 part. $\endgroup$ – Larry May 2 '15 at 13:30
  • $\begingroup$ Recall that the formula for the slope for a nonvertical line is $y=mx+b$, where $m$ is the slope$ and $b$ is the y-intercept, the part of the line that crosses the y-axis. The remainder of the variables go to their corresponding coordinates for any number you substitute for either of them first. $\endgroup$ – ReliableMathBoy May 2 '15 at 13:52
  • $\begingroup$ hooneedaalgebra? 2 - 5dy/dx = 0 $\endgroup$ – bjb568 May 2 '15 at 14:08
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$$5y=2x-10\iff y=\dfrac25x-\dfrac{10}5$$

Compare with $y=mx+c$

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The formula for the slope of a nonvertical line is $y=mx+b$, so do it this way:$$2x-5y=10$$Subtract $2x$ from each side:$$-5y=10-2x$$Rearrange the number and the coefficient of $x$ (count the variable and attach it to the coefficient) on the second side:$$-5y=-2x+10$$Divide each side by the coefficient of $y$, which is $-5$:$$y={2\over5}x-2$$and there you have it! The slope for the equation is $2\over5$ plus a y-intercept of $-2$.

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  • $\begingroup$ The formula for the slope of a non-vertical line through points $(x_1, y_1)$ and $(x_2, y_2)$ is $$m = \frac{y_1 - y_2}{x_1 - x_2} = \frac{y_2 - y_1}{x_2 - x_1}$$ The equation $y = mx + b$, where $m$ is the slope and $b$ is the $y$-intercept, is called the slope-intercept form of the equation of a line. $\endgroup$ – N. F. Taussig May 3 '15 at 21:07
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The slope of a line is a rate of change and is represented by m. 

  Slope=Vertical change/Horizontal change=Rise/Run

When a line passes through the points

$(x_1, y_1)$ and $(x_2, y_2)$, the slope is $m = \frac{y_2-y_1}{x_2-x_1}$

source:http://math.tutorpace.com

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There is also the option of using the short cut that Ax + By = C always has a slope of -A/B.

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