# Equation of straight line

1. Aug 24, 2011

### nae99

1. The problem statement, all variables and given/known data

find the equation of the straight line which is perpendicular to the line 5x-3y-6=0 and passes through the point (-3,4)

2. Relevant equations

3. The attempt at a solution
-3y=-5x+6

where do i go from there

Last edited: Aug 24, 2011
2. Aug 24, 2011

### dynamicsolo

Finish putting the equation for the line into slope-intercept form, so that you can read what the slope is. What is the relationship between the slopes of two perpendicular lines? You can use that to find the slope of the line you are seeking. You are given a point which this new line must pass through, so you can get its equation from the point-slope form for a line.

3. Aug 24, 2011

### nae99

-3y=-5x+6

-3(4)=-5(-3) + 6
-12=15+6
-12=21

should it be done like that

4. Aug 24, 2011

### dynamicsolo

If you're getting -12 = 21 , then that probably isn't what you need to do... You don't want to put ( -3, -4 ) into the original line's equation, because that point is not on the line you were given.

What is the slope-intercept form for -3y = -5x + 6 ? (What do you still need to do?)

Once you've done that, what does the equation tell you about the slope of this line you were given?

5. Aug 24, 2011

### nae99

honestly i have no idea what is slope intercept

6. Aug 24, 2011

### phinds

Then this problem is probably too advanced for you.

7. Aug 24, 2011

### DaveC426913

1] Reformulate the equation in the form of y=mx+b.
2] Do you know how to calculate the slope of a line? Rise over run?

Last edited: Aug 24, 2011
8. Aug 24, 2011

### HallsofIvy

Staff Emeritus
Do you know what is meant by the slope of a line? If not, then, as phinds says, you shouldn't be attempting a problem like this. If it hs been given as coursework, then you should consult your text book for the definition of "slope" and how the slopes of perpendicular lines are related.

9. Aug 28, 2011

### apit3g

i suggest use y=mx+c....frst find the slope of the equation..n use y1-y2/x2-x2=....

10. Aug 28, 2011

### Staff: Mentor

Your expression needs parentheses. If a line contains the points (x1, y1) and (x2, y2), then the slope m is given by m = (y2 - y1)/(x2 - xSUB]1[/SUB])

The expression you wrote would be interpreted to mean
$$y_1 - \frac{y_2}{x_2} - x_1$$
but that's not what you meant.