Slope and value calculation assistance

[tathagata7]

On my SSAT prep I have the below problem:

A line with a slope of 2 passes through points (k,3) and (6,k) on the coordinate grid. What is the value of k?

Solving for the answer 5

I've been searching for a process on-line.

If someone can just start me off, it would be helpful.

Thank you

 

[tathagata7]

Using the point slope formula, is this correct so far?

2 = (3-k)/(k-6)

Thanks

 

[Otis]

Using the point slope formula, is this correct so far?

2 = (3-k)/(k-6)

Yes, although I would have written it like:

3 - k = 2(k - 6)

Now, solve for k.

 

[tathagata7]

Yes, although I would have written it like:

3 - k = 2(k - 6)

Now, solve for k.

Got it! But isn't the formula to memorize for the exam is:

m = (Y1 - Y2)/(X1-X2) ?

 

[Otis]

m = (Y1 - Y2)/(X1-X2)

That's the slope formula.

In your previous post, you wrote that you were using the point-slope formula, so that's the form that I used.

Either formula works, for this exercise. :cool:

 

[tathagata7]

This is not a topic they covered in my math class in the 8th grade yet.

Since I may be facing a similar type of problem on the SSAT exam, any suggestions on what formula to memorize?

Thanks for everything!

 

[Harry_the_cat]

This is not a topic they covered in my math class in the 8th grade yet.

Since I may be facing a similar type of problem on the SSAT exam, any suggestions on what formula to memorize?

Thanks for everything!

Remember the one you wrote ie m = (Y1 - Y2)/(X1-X2).

Better still understand it! Slope is defined as \(\displaystyle \frac{rise}{run}\). Y1 - Y2 = rise and X1 - X2 = run.

If you then multiply both sides by (X1 - X2) you'll get m(X1 - X2) = (Y1 - Y2) which gets rid of the fraction so you can solve the equation.

They are really the same formula, just written in a different form.

 

[Otis]

This is not a topic they covered in my math class in the 8th grade yet.

What topic? The point-slope formula?

You posted that you used the point-slope formula, but then you wrote the slope formula, so I'm not sure how you started.

Again, for this exercise, either the slope formula or the point-slope formula may be used.

... any suggestions on what formula to memorize?

This would be a good question to ask your teacher.

My suggestion is to have a working knowledge of each of the elementary formulas used with linear equations.