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# Slope-intercept equation from slope & point: fractions (old)

An old video where Sal finds the slope-intercept form of a line that has a slope of ⅓ and goes through the point (-12,-14/3). Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• Why is 'b' considered the y-intercept and why is 'y' in y = mx + b
• Armin,
The y intercept is when x=0.
For the equation y=mx+b,
if x = 0 then y=m*0+b so when x=0, then y=b.
So the y intercept is the point (0,b).

I hope that helps make it click for you.
• If the slope is -5/14 and point is -1/2 Is the y intercept 1.642857
Should the answer be a fraction?
• i need help on graphing this equation y = 1/4x
• Try applying y = mx + b where m is the slope and b is the y-intercept.

In your equation, m would equal 1/4 and b = 0 (b is not mentioned so it is therefore 0)

If b = 0, we know that the line intercepts the y-axis at 0.

If m = 1/4 then the slope of the line is 4 units across to the right and 1 unit up.

So plot a line that goes through coordinates (0,0) and (4,1) and so on.

Hope that helps. It's hard to explain without a diagram.
• How do I rewrite the equation 6y-5x=11 in slope-intercept form?
• In y=mx+b, what does b represent?
• b is your y-intercept (where the line crosses the y-axis)
(1 vote)
• How do you find a slope for a line equation: 3x- 2y= 7
(1 vote)
• First write it in the form y = ax + b, where a will be the slope:
3x - 2y = 7;
2y = 3x - 7;
y = (3/2)x - 7/2.
We observe that the slope of the line is 3/2.
• Comment
Sal had the following equation: -14/3 = 1/3(-12)+b above. Instead of dividing by the denominator of 1/3, 3 into 12 to get -4, he should have just multiplied 1/3 times -12 to get -12/3. Than he could have added +12/3 to both sides of the equation, and the terms would have already been in their common denominator form. Sal than had to than reestablish 4 as 12/3 which he already had on the other side. Not a mistake, but an opportunity to keep the terms already in their common denominator form missed
• Sal may have done this to show everybody the step-by-step procedures that one might have done.
(1 vote)
• I am doing this one problem and it goes like this for a fractional slope:
y=-1/3x-3 can you help me with this one?
(1 vote)
• I assume you are trying to graph the line (you didn't say).

First, graph the y-intercept (0, -3). Then use the slope to find more points.

You have a negative slope, so you know the line slants down from left to right. When you have a negative slope to use fo graphing, you put the minus on one of the two numbers.

Starting from the y-intercept, you can do either of the following movements to get more points:
(-1)/3 = Go down 1 and right 3
1/(-3) = Go up 1 and left 3

Hope this helps.