• Welcome! The new FreeMathHelp.com forum is live. We've moved from VB4 to Xenforo 2.1 as our underlying software. Hopefully you find the upgrade to be a positive change. Please feel free to reach out as issues arise -- things will be a little different, and minor issues will no doubt crop up.

I' m stuck in the middle of this problem

wj0126_9

New member
Joined
Jan 21, 2010
Messages
3
My Problem is to Find the equation of the line having the givin slope and containing the given point,

Here is the problem and how I solve it which is wrong.

M=7/8, (7,-6)

I use the point and slope formula to solve

y-(9)=7/8 (x-(2))
y+9=7/8 (x-2)
y+9=7/8x + 16/8 + -9/1*8/8 =72/8

y+7/8x -11

I'm missing up the fractions part please help...I'm DEAD IN THE WATER right now/////
 

mmm4444bot

Super Moderator
Staff member
Joined
Oct 6, 2005
Messages
10,158
wj0126_9 said:
M=7/8, (7,-6)

I use the point and slope formula to solve

y - (9) = 7/8 (x- (2) )
We don't need parentheses around numbers.

y - 9 = 7/8 * (x - 2)

Why did you substitute in the coordinates (2, 9) instead of (7, -6) ?
 

wj0126_9

New member
Joined
Jan 21, 2010
Messages
3
Ok, it should have been (2,9) I'm seeing double about now, I'm been at this for 2 hours...sorry....
 

mmm4444bot

Super Moderator
Staff member
Joined
Oct 6, 2005
Messages
10,158
wj0126_9 said:
y-(9)=7/8 (x-(2))
y+9=7/8 (x-2)
y+9=7/8x + 16/8 + -9/1*8/8 =72/8
Okay, with given coordinates (2, 9), you've got an equation for the line.

y - 9 = 7/8 * (x - 2)

Now, if you've been asked to put this into Slope-Intercept form, then solve for y.

We don't change y - 9 into y + 9 (I'm not sure why you did that).

On the other side, we distribute 7/8 across the difference x - 2 using the Distributive Property.

\(\displaystyle y \;-\; 9 \;=\; \frac{7}{8} \cdot x \;-\; \frac{7}{8} \cdot \frac{2}{1}\)

Can you multiply 7/8 times 2, to simplify that product? Then add 9 to both sides of the equation.

BTW: What are the instructions for this exercise?
 

wj0126_9

New member
Joined
Jan 21, 2010
Messages
3
The instructions for the problem is "Find the equation of the line having the givin slope and containing the given point."

Thanks for the help, so when I use the distributive property 7/8 becomes a NEGATIVE -7/8 * 2/1 which would equal 14/8. Then I bring the 9 over and say 9/1 * 8/8 = 72/8 is this correct?
 

mmm4444bot

Super Moderator
Staff member
Joined
Oct 6, 2005
Messages
10,158
wj0126_9 said:
The instructions for the problem is "Find the equation of the line having the givin slope and containing the given point."
y - 9 = 7/8 * (x - 2)

This is an equation for the line with slope 7/8 passing through the given point (2, 9).

You're done. :cool:
 

mmm4444bot

Super Moderator
Staff member
Joined
Oct 6, 2005
Messages
10,158
wj0126_9 said:
so when I use the distributive property 7/8 becomes a NEGATIVE -7/8 * 2/1 which would equal 14/8. -7 times 2 is not 14

Then I bring the 9 over and say 9/1 * 8/8 = 72/8 is this correct? No; "bring the 9 over" means ADD. What's up with 8/8?
\(\displaystyle \frac{-7}{8} \cdot \frac{2}{1} \;=\; \frac{-14}{8} \;=\; \frac{-7}{4}\)

So we have:

\(\displaystyle y \;-\; 9 \;=\; \frac{7}{8} \cdot x \;-\; \frac{7}{4}\)

Add 9 to both sides, to solve for y, if you want to solve for y, but you don't need to do any of this, with the instructions you were given.

\(\displaystyle y \;=\; \frac{7}{8} \cdot x \;-\; \frac{7}{4} + 9\)

If you cannot add 7/4 + 9, then you might want to review some stuff HERE.
 
Top