The diagram shows part of the curve y=5+4e2xy = 5 + \frac{4}{e^{2x}} intersecting the yy-axis at point PP.
The tangent to the curve at point PP intersects the xx-axis at QQ.
Find the area of the shaded region.

Work through it with AI →

It won't just hand you the answer — it asks where you're stuck.How the checker works

Worked solution

11

1. Find the coordinates of point $P$ (the $y$-intercept of the curve).

At the yy-axis, x=0x = 0.
y=5+4e0=5+4=9y = 5 + \frac{4}{e^{0}} = 5 + 4 = 9
So, PP is (0,9)(0, 9).

2. Find the gradient of the tangent at $P$.

y=5+4e−2xy = 5 + 4e^{-2x}
dydx=4(−2)e−2x=−8e−2x\frac{dy}{dx} = 4(-2)e^{-2x} = -8e^{-2x}
At x=0x = 0, dydx=−8e0=−8\frac{dy}{dx} = -8e^{0} = -8

3. Find the equation of the tangent at $P$ and the coordinates of $Q$.

Equation of tangent: y−9=−8(x−0)  ⟹  y=−8x+9y - 9 = -8(x - 0) \implies y = -8x + 9
At QQ, the tangent intersects the xx-axis, so y=0y = 0.
0=−8x+9  ⟹  x=980 = -8x + 9 \implies x = \frac{9}{8}
So, QQ is (98,0)(\frac{9}{8}, 0).

4. Set up the integral for the area of the shaded region.

The shaded region is bounded by the curve and the tangent from x=0x = 0 to x=98x = \frac{9}{8}.
Area = ∫098((5+4e−2x)−(−8x+9))dx\int_{0}^{\frac{9}{8}} \left( (5 + 4e^{-2x}) - (-8x + 9) \right) dx
Area = ∫098(4e−2x+8x−4)dx\int_{0}^{\frac{9}{8}} (4e^{-2x} + 8x - 4) dx

5. Evaluate the definite integral.

∫(4e−2x+8x−4)dx=[4e−2x−2+8x22−4x]098\int (4e^{-2x} + 8x - 4) dx = \left[ \frac{4e^{-2x}}{-2} + \frac{8x^2}{2} - 4x \right]_{0}^{\frac{9}{8}}
=[−2e−2x+4x2−4x]098= \left[ -2e^{-2x} + 4x^2 - 4x \right]_{0}^{\frac{9}{8}}
=(−2e−2(98)+4(98)2−4(98))−(−2e0+0−0)= \left( -2e^{-2(\frac{9}{8})} + 4\left(\frac{9}{8}\right)^2 - 4\left(\frac{9}{8}\right) \right) - \left( -2e^{0} + 0 - 0 \right)
=(−2e−94+4(8164)−92)−(−2)= \left( -2e^{-\frac{9}{4}} + 4\left(\frac{81}{64}\right) - \frac{9}{2} \right) - (-2)
=−2e−94+8116−7216+3216= -2e^{-\frac{9}{4}} + \frac{81}{16} - \frac{72}{16} + \frac{32}{16}
=4116−2e−94= \frac{41}{16} - 2e^{-\frac{9}{4}}

Answer

4116−2e−94\frac{41}{16} - 2e^{-\frac{9}{4}} or 2.352.35 (to 3 s.f.)

AI analysis — may contain mistakes.

Worked this one out on paper? Snap your steps and Gigle's AI math checker will circle the step where it went wrong.

More questions on this topic

  1. 1The figure shows part of the curve y=g(x)y = g(x). (2,8)(2, 8) and (6,1)(6, 1) are two points on the curve. Given that ∫26y dx=32\int_{2}^{6} y \text{ } dx = 32…
  2. 2The diagram shows part of the curve y=3e−12x−6y = 3e^{-\frac{1}{2}x} - 6 which crosses the xx-axis at PP and the yy-axis at QQ…
  3. 3The diagram shows part of the curve y=3x+4y = \sqrt{3x + 4}. The line ABAB is tangent to the curve at AA. The points BB an…
  4. 4The diagram shows part of the curve y=(1−x)(x−4)y = (1 - x)(x - 4) and two lines l1l_1 and l2l_2. The lines l1l_1 and l2l_2 are ta…
  5. 5The diagram below shows the graph of y=12x+1y = \frac{1}{2x+1} and the tangent to the curve where the curve intersects the yy…