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y. y. y = f ( x ). y = g ( x ). x. x. a. b. a. b. Shaded Area =. Shaded Area =. Section 5.3: Finding the Total Area. y= f ( x ). y= f ( x ). y= f ( x ). y = g ( x ). y = g ( x ). a. a. b. b. y = g ( x ). Area under f ( x ) =. Area under g ( x ) =. a. b.
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y y y = f(x) y = g(x) x x a b a b Shaded Area = Shaded Area = Section 5.3: Finding the Total Area
y= f(x) y= f(x) y= f(x) y = g(x) y = g(x) a a b b y = g(x) Area under f(x)= Area under g(x)= a b A) Area Between Two Curves in [a , b] Area between f(x)and g(x)
y y = g(x) y y = f(x) y = 0 y = 0 a b x x a b B) Area Between a Curve and the x-Axis in [a , b] x-Axis is same as y = 0 Top Function is y = 0 Top Function is y = f(x) Bottom Function is y = g(x) Bottom Function is y = 0 Area under f(x) in[a , b]: Area under g(x) in[a , b]:
y y = 2x- 1 y = x2 - 4 x b a C) Area Between Intersecting Curves Example: Find the area between the graph y= x2 - 4and y = 2x- 1 1) Graph both functions 2) Find the points of intersection by equating both functions: y = y x2 - 4 = 2x- 1 x2 - 2x- 3 = 0 (x+ 1)(x- 3) = 0 x = -1 , x = +3 3) Area Top Function is 2x- 1, Bottom Function is x2 - 4
y y = x2 - 4x +3 x 1 3 y = 0 Example: Find the area between the graph y = x2 -4x + 3and the x-axis 1) Graph the function with the x-axis (or y = 0) 2) Find the points of intersection by equating both functions: y = y x2 -4x + 3= 0 (x- 1)(x- 3) = 0 x = 1 , x = 3 3) Area Top Function is y = 0, Bottom Function is y = x2 -4x + 3
y= x2 – 4 y y = 0 3 -1 -2 2 x A2= 2.33 A1= 9 = 9 + 2.33 = 11.33 D)Area Between Curves With Multiple Points of Intersections (Crossing Curves) Example: Find the area enclosed by the x-axis, y = x2 - 4, x = -1 and x = 3 1) Graph the function y = x2 - 4 with the x-axis (or y = 0), Shade in the region between x = -1 and x = 3 2) Find the points of intersection by equating both functions: y = y or (x- 2)(x+ 2) = 0 x2 -4= 0 x = 2 , x = -2 y = x2 - 4 and the x-axis cross each others x = -2, x = 2 3) Area
y = x3 y y = x x 1 -1 0 A2= 0.25 A1= 0.25 , the answer will be zero. Note: if you write Area = Example: Find the area enclosed by y = x3 and y = x 1) Graph the function y = x3 , and y = x 2) Find the points of intersection by equating both functions: y = y or x3 - x = 0 x3 = x x(x2 - 1) = 0 x(x- 1)(x + 1) = 0 x = 0 , x = -1 , x = 1 The graphs cross at x = -1, x = 0 and x = 1 3) Area = 0.5 + 0.25 = 0.25