Posted by **Esther** on Wednesday, January 26, 2011 at 11:14pm.

write an equation of the line containing the point and perpendicular to the given line (4,-8); 2x+5y=4

I am having a very hard time, but I'm trying hard to study the steps for solving the problem.

Profoundly, thank you.

- Algebra 1 -
**helper**, Wednesday, January 26, 2011 at 11:21pm
Did you see the answer to your post below?

Post your work so I can see where you are having trouble.

- Algebra 1 -
**Esther**, Wednesday, January 26, 2011 at 11:49pm
Sorry, but, no, I didn't see the answer to my post. However,

(4,-8); 2x+5y=4 is?

y=-2x+4

y-8=1/2

y-8=1/2(x-4)

Again, I don't really know what to do after this. I may not even be followin the steps right. However, I would really appreacite your help. Thank you a million.

- Algebra 1 -
**helper**, Thursday, January 27, 2011 at 12:27am
2x + 5y = 4

Add -2x to both sides

5y = -2x + 4

divide both sides by 5

y = -2/5 y + 4/5

So, slope m = -2/5

Perpendicular lines, the slopes are negative reciprocals of each other.

Slope = -2/5

m1 * m2 = -1

-2/5 * m2 = -1

m2 = -1/(-2/5)

m2 = 5/2

Now you have to find b, for the equation of the perpendicular line.

y = mx + b

m = 5/2

y = 5/2 x + b

P(4, -8)

-8 = 5/2 (4) + b

-8 = 20/2 + b

-8 = 10 + b

-18 = b

y = 5/2 x + b

y = 5/2 + -18

y = 5/2 - 18

Follow these exact steps.

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