It is $1.21 per song downloaded
Answer:
2n - 4.
Step-by-step explanation:
(n+8) + (n−12)
= n + 8 + n - 12
= n + n + 8 - 12
= 2n - 4.
Answer:
$392
Step-by-step explanation:
Given the expression :
Total cost = 20a + 13c
a = adult
c = student
The total cost for 4 adults and 24 students
a = 4 ; c = 24
Total cost :
20(4) + 13(24)
80 + 312
= $392
Answer:

Step-by-step explanation:

Answer:
(e) csc x − cot x − ln(1 + cos x) + C
(c) 0
Step-by-step explanation:
(e) ∫ (1 + sin x) / (1 + cos x) dx
Split the integral.
∫ 1 / (1 + cos x) dx + ∫ sin x / (1 + cos x) dx
Multiply top and bottom of first integral by the conjugate, 1 − cos x.
∫ (1 − cos x) / (1 − cos²x) dx + ∫ sin x / (1 + cos x) dx
Pythagorean identity.
∫ (1 − cos x) / (sin²x) dx + ∫ sin x / (1 + cos x) dx
Divide.
∫ (csc²x − cot x csc x) dx + ∫ sin x / (1 + cos x) dx
Integrate.
csc x − cot x − ln(1 + cos x) + C
(c) ∫₋₇⁷ erf(x) dx
= ∫₋₇⁰ erf(x) dx + ∫₀⁷ erf(x) dx
The error function is odd (erf(-x) = -erf(x)), so:
= -∫₀⁷ erf(x) dx + ∫₀⁷ erf(x) dx
= 0