6. Solve the following first-order linear differential equations; if an initial condition is given, definitize the arbitrary constant: (a) 2 + 12y + 2et = 0, y(0) = /; (b) dy+y=t

4. Let A = {a, b, c, d, e, f}, B = {e, f, g, h} and C = {a, e, h,i}. Let U = {a, b, c, d, e, f, g, h, i, j, k}. • Draw a Venn Diagram to describe the relationships between these sets Find (AB) NC • Find (AC) UB Find AUBUC • Find (BC) N (A - C)

7. A consumer lives on an island where she produces two goods x and y according to the production possibility frontier x² + y² < 200 and she consumes all the goods. Her utility function is U(x, y) = x y³. She faces an environmental constraint on her total output of both goods. The environmental constraint is given by x + y ≤20. • (a) Write down the consumer's optimization problem. (b) Write out the Kuhn-Tucker first order conditions. (c) Find the consumer's optimal consumption bundle (x*, y*).

3. Answer the following questions: (a) Given the marginal propensity to import M'(Y) = 0.1 and the information that M = 20 when Y = 0, find the import function M(Y). (b) Given a continuous income stream at the constant rate of $1,000 per year, what will be the present value II if the income stream terminates after exactly 3 years and the discount rate is 0.04? (c) What is the present value of a perpetual cash flow of $2,460 per year, discounted at r = 8%?

5. Let A and B be arbitrary sets. Prove AnB = AUB.

2. Answer the following questions: (a) Given the marginal-revenue function R'(Q) = 28Q - €0.3Q, find the total-revenue function R(Q). What initial condition can you introduce to definitize the constant of integration? = (b) Given the marginal propensity to consume C'(Y) 0.80.1Y-1/2 and the information that C = Y when Y = 100, find the consumption function C(Y).

7. Let X, A, and B be arbitrary sets such that ACX and BC X. Prove AUB CX.

1. Write out the following sets as a list of elements. If necessary you may use ... in your description. {x EZ: |x|< 10 A x < 0} {x ЄN: x ≤ 20 A x = 2y for some y = N} {n EN: 3 | n^ 1 < n < 20} {y Є Z: y² <0}

3. For each statement below, write an equivalent statement using the justification given. = y Є A or yЄ B by the definition of union = y Є A or y Є B by the definition of set complement = x = C and x & D by DeMorgan's Law =Vx (x EnFxЄEUF) by definition of subset. = (X CYUZ)A (YUZ CX) by definition of set equality