Step-by-step explanation:

Answer:
40 pencil cases
Step-by-step explanation:
To find out how many $2.50 pencil cases you can buy with $100, you need to divide. Dividing the amount of money you have by the cost of the item will get you the amount of items you can buy. 100 divided by 2.50 is 40. So, you can get 40 cases.
Answer:

Step-by-step explanation:
y′′ + 4y′ − 21y = 0
The auxiliary equation is given by
m² + 4m - 21 = 0
We solve this using the quadratic formula. So

So, the solution of the equation is

where m₁ = 3 and m₂ = -7.
So,

Also,

Since y(1) = 1 and y'(1) = 0, we substitute them into the equations above. So,


Substituting A into (1) above, we have

Substituting B into A, we have

Substituting A and B into y, we have

So the solution to the differential equation is

Answer:idk why u ask? ? ? ?
Step-by-step explanation: