SOLUTION: How do I find the reciprocal of x? The equation is y = x + 4 and the perpendicular line must pass through point (-7, 1). Please help me, thanks! Teresa Kelley

Click here to see ALL problems on Graphs

Question 932360: How do I find the reciprocal of x? The equation is y = x + 4 and the perpendicular line must pass through point (-7, 1). Please help me, thanks! Teresa Kelley
Found 2 solutions by jim_thompson5910, josgarithmetic:
Answer by jim_thompson5910(35256) (Show Source):
You can put this solution on YOUR website!
You don't find the negative reciprocal of x. You find the negative reciprocal of the slope.

y = x+4 is the same as y = 1x + 4

The slope is 1 since that is the coefficient for x.

Original Slope: 1 = 1/1

Perpendicular slope: 1/1 ---> -1/1 = -1

-------------------------------------------------------

The perpendicular slope is -1

y = mx+b

y = -1x + b ... plug in the perpendicular slope

1 = -1*(-7) + b ... plug in the point (x,y) = (-7,1)

1 = 7 + b

1 - 7 = b

-6 = b

b = -6

So the equation of the perpendicular line is y = -x - 6

------------------------------------------------------------------------------------------------------------------------

If you need more one-on-one help, email me at jim_thompson5910@hotmail.com. You can ask me a few more questions for free, but afterwards, I would charge you ($2 a problem to have steps shown or $1 a problem for answer only).

Alternatively, please consider visiting my website: http://www.freewebs.com/jimthompson5910/home.html and making a donation. Any amount is greatly appreciated as it helps me a lot. This donation is to support free tutoring. Thank you.

Jim
------------------------------------------------------------------------------------------------------------------------

Answer by josgarithmetic(39630) (Show Source):
You can put this solution on YOUR website!
Why just find x instead of further finding reciprocal?

You want to know the equation for the line perpendicular and containing point (-7,1), and then find the intersection of this with the given line, with most interest on the x value.

GIVEN , FIND equation of line of slope -1 which contains (-7,1). This line is according to point-slope form.

-
Equate the two expressions for y, between the two different lines.

-
Reciprocal wanted is .