MHB Quick problem: given the slope and a point, find the line

AI Thread Summary
The discussion centers on finding the equation of a line with a given slope of 5/6 that passes through the point (1,3). The correct equation derived using the slope-intercept form is y = (5/6)x + (13/6). However, the answer provided in the book is incorrect, featuring the wrong slope. The point-slope formula is recommended for clarity, confirming that the user's solution is accurate despite the book's errors. Confidence in one's mathematical skills is emphasized as essential for identifying mistakes in published answers.
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Hello,

I am working on a problem. I am trying to get an equation for this linear line with these traits:

slope = 5/6

linear equation that passes through [1,3]therefore using this formula

y=mx+b

3=5/6[1]+b

b=13/6

therefore, the equation is

y=5/6[x] + 13/6

However, the answer given is

y - ( 3 ) = (5/6) ( x - ( 1 ) ) ,

or

y = (7/6) x + (13/6) .Any pointers,

Thanks, Tim
 
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The second given answer has the wrong slope. I would recommend using the point-slope formula because you are given exactly what you need to use this formula, that is a point on the line and its slope.

This formula is:

$$y-y_1=m\left(x-x_1 \right)$$

Now, you are given:

$$m=\frac{5}{6}$$

and:

$$\left(x_1,y_1 \right)=(1,3)$$

And so plugging in the given data to our formula, we obtain:

$$y-3=\frac{5}{6}(x-1)$$

If we wish to put this into slope-intercept form, we may distribute the slope on the right side:

$$y-3=\frac{5}{6}x-\frac{5}{6}$$

and add the equation:

$$3=\frac{18}{6}$$

to get:

$$y=\frac{5}{6}x+\frac{13}{6}$$

So you had the correct answer in slope-intercept form, but the answer given by your book is incorrect for this form (the slope is wrong, most likely just a typo), but is correct for the point-slope form.
 
A persistent problem with many math texts is that "answers" given in the "back of the book" often contain silly mistakes (apparently, good proof-readers are hard to find).

The only remedy for this is to become so confident in YOUR skills, that you can TELL when the answer is right or wrong.

You answered the problem correctly, so well done!
 
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