Analyze the function h(x) = x3 - 2x2 - 15x, finding intercepts and stationary points.
|Mathematics
Analyze the function h(x) = x3 - 2x2 - 15x, finding intercepts and stationary points.
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(0,0)
asanda, let's knock this out.
Let's complete the analysis for function (c) h(x)=x3−2x2−15x.
Step 1: Find the intercepts with the axes.
To find the y-intercept, set x=0:
h(0)=(0)3−2(0)2−15(0)=0
The y-intercept is ∗(0,0)∗.
To find the x-intercepts, set h(x)=0:
x3−2x2−15x=0
Factor out x:
x(x2−2x−15)=0
Factor the quadratic expression:
x(x−5)(x+3)=0
This gives the x-intercepts: x=0, x=5, and x=−3.
The x-intercepts are ∗(0,0),(5,0),and(−3,0)∗.
Step 2: Find the stationary points.
First, find the first derivative h′(x):
h′(x)=dxd(x3−2x2−15x)=3x2−4x−15
Set h′(x)=0 to find the x-coordinates of the stationary points:
3x2−4x−15=0
Using the quadratic formula x=2a−b±b2−4ac:
x=2(3)−(−4)±(−4)2−4(3)(−15)x=64±16+180x=64±196x=64±14
The x-coordinates are:
x1=64+14=618=3x2=64−14=6−10=−35
Now, find the corresponding y-coordinates by substituting these values back into h(x):
For x=3:
h(3)=(3)3−2(3)2−15(3)=27−18−45=−36
Stationary point 1: (3,−36).
For x=−35:
h(−35)=(−35)3−2(−35)2−15(−35)h(−35)=−27125−2(925)+25h(−35)=−27125−950+25h(−35)=27−125−150+675=27400
Stationary point 2: (−35,27400).
Step 3: Determine the nature of the stationary points.
Find the second derivative h′′(x):
h′′(x)=dxd(3x2−4x−15)=6x−4
Evaluate h′′(x) at each stationary point:
For x=3:
h′′(3)=6(3)−4=18−4=14
Since h′′(3)>0, (3,−36) is a local minimum.
For x=−35:
h′′(−35)=6(−35)−4=−10−4=−14
Since h′′(−35)<0, (−35,27400) is a local maximum.
The stationary points are ∗(3,−36)(localminimum)and(−35,27400)(localmaximum)∗.
Step 4: Find the point of inflection.
Set h′′(x)=0:
6x−4=06x=4x=64=32
Now, find the corresponding y-coordinate by substituting x=32 into h(x):
h(32)=(32)3−2(32)2−15(32)h(32)=278−2(94)−10h(32)=278−98−10h(32)=278−24−270=27−286
The point of inflection is ∗(32,−27286)∗.
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ScanSolve AI Answer
asanda, let's knock this out. Let's complete the analysis for function (c) h(x) = x^3 - 2x^2 - 15x. Step 1: Find the intercepts with the axes. To find the y-intercept, set x=0: h(0) = (0)^3 - 2(0)^2 - 15(0) = 0 The y-intercept is (0,0). To find the x-intercepts, set h(x)=0: x^3 - 2x^2 - 15x = 0 Factor out x: x(x^2 - 2x - 15) = 0 Factor the quadratic expression: x(x-5)(x+3) = 0 This gives the x-intercepts: x=0, x=5, and x=-3. The x-intercepts are (0,0), (5,0), and (-3,0). Step 2: Find the stationary points. First, find the first derivative h'(x): h'(x) = (d)/(dx)(x^3 - 2x^2 - 15x) = 3x^2 - 4x - 15 Set h'(x)=0 to find the x-coordinates of the stationary points: 3x^2 - 4x - 15 = 0 Using the quadratic formula x = -b ± sqrt(b^2 - 4ac)2a: x = -(-4) ± sqrt((-4)^2 - 4(3)(-15))2(3) x = 4 ± sqrt(16 + 180)6 x = 4 ± sqrt(196)6 x = (4 ± 14)/(6) The x-coordinates are: x_1 = (4 + 14)/(6) = (18)/(6) = 3 x_2 = (4 - 14)/(6) = (-10)/(6) = -(5)/(3) Now, find the corresponding y-coordinates by substituting these values back into h(x): For x=3: h(3) = (3)^3 - 2(3)^2 - 15(3) = 27 - 18 - 45 = -36 Stationary point 1: (3, -36). For x=-(5)/(3): h(-(5)/(3)) = (-(5)/(3))^3 - 2(-(5)/(3))^2 - 15(-(5)/(3)) h(-(5)/(3)) = -(125)/(27) - 2((25)/(9)) + 25 h(-(5)/(3)) = -(125)/(27) - (50)/(9) + 25 h(-(5)/(3)) = (-125 - 150 + 675)/(27) = (400)/(27) Stationary point 2: (-(5)/(3), (400)/(27)). Step 3: Determine the nature of the stationary points. Find the second derivative h''(x): h''(x) = (d)/(dx)(3x^2 - 4x - 15) = 6x - 4 Evaluate h''(x) at each stationary point: For x=3: h''(3) = 6(3) - 4 = 18 - 4 = 14 Since h''(3) > 0, (3, -36) is a local minimum. For x=-(5)/(3): h''(-(5)/(3)) = 6(-(5)/(3)) - 4 = -10 - 4 = -14 Since h''(-(5)/(3)) < 0, (-(5)/(3), (400)/(27)) is a local maximum. The stationary points are (3, -36) (local minimum) and (-(5)/(3), (400)/(27)) (local maximum). Step 4: Find the point of inflection. Set h''(x)=0: 6x - 4 = 0 6x = 4 x = (4)/(6) = (2)/(3) Now, find the corresponding y-coordinate by substituting x=(2)/(3) into h(x): h((2)/(3)) = ((2)/(3))^3 - 2((2)/(3))^2 - 15((2)/(3)) h((2)/(3)) = (8)/(27) - 2((4)/(9)) - 10 h((2)/(3)) = (8)/(27) - (8)/(9) - 10 h((2)/(3)) = (8 - 24 - 270)/(27) = (-286)/(27) The point of inflection is ((2)/(3), -(286)/(27)) . What's next?