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Test Review. § 4.1. 1. Know the power rule for integration. a. ∫ (x 4 + x + x ½ + 1 + x – ½ + x – 2 ) dx =. Remember you may differentiate to check your work!. 1. Test Review. Step 1. Find a formula for its value after t years. We need the integral of f ‘ (x) or.
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Test Review § 4.1 1. Know the power rule for integration. a. ∫ (x 4 + x + x ½ + 1 + x – ½ + x – 2) dx = Remember you may differentiate to check your work! 1
Test Review Step1 Find a formula for its value after t years. We need the integral of f ‘ (x) or V = ∫ 300 x 1/2 dx § 4.1 2. Know the three steps in an application problem. A $20,000 art collection is increasing in value at the rate of 300√x dollars per year after x years. V = 300 ∫ x 1/2 dx = 200 x 3/2 + C Step 2 Find the value of C. Note we are given the value of $20,000 when x = 0. 20,000 = (200) (0 3/2 ) + C so 20,000= C and V = 200 x 3/2 + 20,000 Remember you may differentiate to check your work! 2
Test Review Step3 Find the value in 25 years. § 4.1 2. Know the three steps in an application problem. A $20,000 art collection is increasing in value at the rate of 300√x dollars per year after x years. V = f (x) = 200 x 3/2 + 20,000 We need f (25) so f (25) = (200) 25 3/2 + 20,000 = We need f (25) so f (25) = (200) 25 3/2 + 20,000 = 200 · 125 + 20,000 = $45,000 3
Test Review Find Find § 4.2 1. Know the exponential rule for integration. 4 Remember you may differentiate to check your work!
Test Review Find § 4.2 2. Know the logarithmic rule for integration. Remember you may differentiate to check your work! 5
4.3General Indefinite Integral Formulas. ∫ un du = ∫ e u du = e u + C Note the chain “du” is present! 6
4.3 Integration by Substitution. Is it “Power Rule”, “Exponential Rule” or the “Log Rule”? Step 1. Select a substitution that appears to simplify the integrand. Use the basic forms in making your choice. Make sure that du is a factor of the integrand. Step 2. Express the integrand entirely in terms of u and du, completely eliminating the original variable. Step 3. Evaluate the new integral. Step 4. Express the antiderivative found in step 3 in terms of the original variable. (Reverse the substitution.) Remember you may differentiate to check your work! 7
4.3 Integration by Substitution Examples 1. ∫ (3x + 5)4 dx Let u = 3x + 5 and then du = 3 dx ∫ (3x + 5)4 3 dx Let u = x 2 + 2x and then du = 2x + 2 dx Remember you may differentiate to check your work! 8
4.3 Integration by Substitution Examples Let u = 2x – 1 then du = 2 dx = 3 ln | 2x – 1| + c Remember you may differentiate to check your work! 9
Test Review § 4.4 1. Know the basics of definite integrals. Get out your calculator and turn it on! 10
Test Review § 4.5 1. Know the Average Value of a Continuous Function f over [a, b]. Don’t forget to divide by b – a! 11
Average Value Problem The temperature at time t hours is T(t) = - 0.3t 2 + 4t + 60 (for 0 t 12). Find the average temperature between time 0 and 10.
4.5 SUMMARY OF AREA PROBLEMS The Area Between Two Curves. Graph y = abs [f (x) – g (x)] in the interval of integration from a to b. In some cases you may need to use minimum to find the interval of integration. That’s it!
Find the area between y = 3 – 2x 2 and y = 2x 2 – 4. • Graph • f (x) = abs [(3 – 2x 2 ) – (2x 2 – 4)] 2. Find the two x-intercepts by using minimum at . 1.32 and - 1.32 3. Integrate over that domain.
Test Review § 4.6 1. Know how to calculate the Consumers’ Surplus. For the demand function d (x) = 200 e – 0.01x, find the consumers’ surplus at a demand level of x = 100. A is given as 100 and the market price d (A) = d (100) = 200 e (– 0.01)(100) = 73.58 $ 5,284 The customers have paid $ 5,284 less than they were willing to pay. A “savings”. 15
Test Review § 4.6 1. Know how to calculate a Gini index. The Lorenz curve for the distribution of income for students at York College is given by f (x) = x 1.5. Find the index of income concentration. Know what the answer means. 16
Don’t Forget The cost, revenue, price, and profit formulas. The average cost, average revenue, average price, and average profit formulas. The marginal cost, marginal revenue, marginal price, and marginal profit formulas. The marginal average cost, marginal average revenue, marginal average price, and marginal average profit formulas.