I' m stuck in the middle of this problem

wj0126_9

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Jan 21, 2010
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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/////
 
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) ?
 
Ok, it should have been (2,9) I'm seeing double about now, I'm been at this for 2 hours...sorry....
 
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?
 
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?
 
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. 8-)
 
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.
 
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