Answer:
first method
<u>2</u><u>2</u>=<u>5</u>
7. x
we cross multiply to get
<u>2</u><u>2</u><u>x</u>= <u>5</u><u>×</u><u>7</u>
22. 22.
x= <u>3</u><u>5</u>
22
=1.59
second method
<u>2</u><u>2</u>=<u>5</u>
7. x
we multiply the denominators to get 7x
then we multiply each term by 7x
7x×<u>2</u><u>2</u> = <u>5</u>×7x
7. x
here the 7 and 7 will cancel out and the x and x will cancel out to get
<u>2</u><u>2</u><u>x</u>= <u>3</u><u>5</u>
22. 22
= 1.59

We want to find
such that
. This means



Integrating both sides of the latter equation with respect to
tells us

and differentiating with respect to
gives

Integrating both sides with respect to
gives

Then

and differentiating both sides with respect to
gives

So the scalar potential function is

By the fundamental theorem of calculus, the work done by
along any path depends only on the endpoints of that path. In particular, the work done over the line segment (call it
) in part (a) is

and
does the same amount of work over both of the other paths.
In part (b), I don't know what is meant by "df/dt for F"...
In part (c), you're asked to find the work over the 2 parts (call them
and
) of the given path. Using the fundamental theorem makes this trivial:


2t-2=26
first you would add 2 to both sides
that equals 2t=28
then you would divide both sides by two
that would give you
t= 14