Step-by-step explanation:
From the statement:
M: is total to be memorized
A(t): the amount memorized.
The key issue is translate this statement as equation "rate at which a subject is memorized is assumed to be proportional to the amount that is left to be memorized"
memorizing rate is
.
the amount that is left to be memorized can be expressed as the total minus the amount memorized, that is
.
So we can write

And that would be the differential equation for A(t).
16x - 5y = -33 First, you subtract 16x from both sides of the
<u>-16x -16x </u> equation
<u>-5y</u> = <u>-16x -33</u> Next, you divide both sides of the equation by -5 to
-5 -5 make "y =" form
y = 16/5x + 33/5
Cosα=x/L
L=x/cosα, we are told that the ladder base is 48 ft from the base of the wall and α=39° so:
L=48/cos39 ft
L≈61.76 ft (to nearest hundredth of a foot)