can someone help me with this equation of a line

It is hard to read your posting.
Is it \(\displaystyle y - \left( {\sqrt 5 - 38} \right) = \left[ {\frac{1}{{2\sqrt 5 }} - 7} \right]\left( {x - 5} \right)\).

If so, what is to be done with that?
 
yes that's it. I need to put it into a line equation. I've tried several times but I am not getting any of the choices i have on my paper.
 
It is in point-slope form: \(\displaystyle \left( {5,\sqrt 5 - 38} \right)\,\& \,m = \left[ {\frac{1}{{2\sqrt 5 }} - 7} \right]\).

What more do you need?
 
jessica716 said:
I am having trouble with adding and multiplying the square roots.
Click to expand...
Do you have a calculator?
 
the original problem is find an equation of the line tangent to f(x)= sqrt x - 7x-3 at 5. I found the derivative of the equation and replaced x with 5 and got m= 1/2sqrt5 -7
 
There are loads of ways to "simplify" (that is, to rearrange) the terms in this equation, due to the radicals and the messiness this engenders. You may have a matching answer, but just aren't recognizing it.

I agree with you on the value of the slope of the tangent: f'(5) = 1/(2 sqrt[5]) - 7. And clearly f(5) = sqrt[5] - 38, so the point is (x, y) = (5, sqrt[5] - 38). The line, in point-slope form, is thus exactly what you said it was.

So you've done the hard part. Good work! :wink:

Now we need to figure out the messy part: Working backwards from the answer options to puzzle out the format the solution-author is wanting. So please reply with the answer options.

Thank you! :D

Eliz.
 
I figured it out i think changing the radicals to decimals the answer i got is (sqrt5 -70/10)x + 1/2sqrt5 -3
 
There are different forms of equation of line.

It seems that - you know what you are supposed to be getting(choices).

Please tell us what those are and show us your work.
 
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