Answer:
That's incorrect. The simplest way to show this is by evaluating the functions at a given point. Let's say x=0, then:
Sin(-x) = Sin(0) = 0
-cos x = -cos (0) = -1
Therefore, Sin(-x)≠-cos x.
Assuming there is no specific percentages in the grade book, you would need a grade of 95 to get your whole grade to 90. You find this out by working backwards starting with 90 to find average. You take 90 times 2 which equals 180 and you subtract 85 from that to get 95! Brainliest?
Separate the variables:

Separate the left side into partial fractions. We want coefficients a and b such that





So we have

Integrating both sides yields






With the initial condition y(0) = 1, we find

so that the particular solution is

It's not too hard to solve explicitly for y; notice that

Then





