Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

Can I please have answers for the following calculus questions?

Just looking to check my answers as the methods done.

(1)

If

f(x)= {x^2 if x<(or equal to)3

{mx+b if x >3

find the values of m and b that make f differentiable everywhere.

(2)

Find the derivative of the function

g(x)=(1x^2 -4x-1)e^x

g'(x)= ?

(3)

let f(x)=(x^2+8x+16)/(6x+24)

f'(5)=?

f''(5)= ?

(4)

Let f(x)= sin(x^5)

f'(x)=?

f'(1)=?

(5)

Let f(x)=2e^(xsinx)

f'(x)=?

(6)

Consider the function f(x)=2x^3+18x^2-162x+5, -9<(or equal to)x<(or equal to)4

Absolute minimum value?

Absolute maximum value?

(7)

Find the x coordinateof the absolute maximum for the function

f(x)=11x-5xln(x), x>0

(8)

Find an equation of the tangent line to the curve y=-1-2x-3x^2 at (1,-6)

y=?

(9)

Use implicit differentiation to find the slope of the tangent line to the curve 3x^2-3xy+3y^3=-192 at the point (-4,-4)

m=?

1 Answer

Relevance
  • Tom
    Lv 5
    8 years ago
    Favorite Answer

    (1)

    If

    f(x)= {x^2 if x<= 3

    .......{mx+b if x >3

    f(x) continuous at x=3 => 3^2 = 3m +b

    differentiable at x=3 => 2(3) = m = 6, so b = -9

    (2)

    Find the derivative of the function

    g(x)=(x^2 -4x-1)e^x

    g'(x)= (x^2 -4x -1)e^x + (2x -4)e^x by product rule,

    = (x^2 -2x -5)e^x

    (3)

    let f(x)=(x^2+8x+16)/(6x+24)

    = (x + 4)^2/ 6(x + 4) = (x + 4)/6 .. x ≠ -4

    f '(5)= 1/6

    f ''(5)= 0

    (4)

    Let f(x)= sin(x^5)

    f '(x)= -(5x^4)cos(x^5) ... chain rule

    f '(1)= -5.cos(1 radian) = -2.702

    (5)

    Let f(x)=2e^(xsinx)

    f '(x)= 2[sinx -xcosx]e^(xsinx)

    (6)

    Consider the function

    f(x)=2x^3 +18x^2 -162x +5, -9<=x<=4

    f '(x) = 6x^2 +36x -162 = 6[x^2 +6x -27] = 6(x +9)(x -3)

    SPs are at x = -9 and x = 3 both in domain interval..

    f ''(x) = 12x + 36 with f ''(-9) <0 so f(-9) a local maxima and

    f ''(3) > 0 a local minima

    boundary values are f(3) = -265 a minima and f(4) = -227

    Absolute minimum value?

    f(3) = -265

    Absolute maximum value?

    f(-9) = 1463

    (7)

    Find the x coordinate of the absolute maximum for the function

    f(x) =11x -5x.ln(x), x>0

    f '(x) = 11 - 5[1 +lnx] = 0 => lnx = 6/5

    f ''(x) = -5(1/x) < 0 so local maximum

    so x_max = e^(6/5) = 3.320

    (8)

    Find an equation of the tangent line to the curve y = -1 -2x -3x^2 at (1,-6)

    dy/dx = -2 -6x

    slope (y = mx + c) = m = -2 -6(1) = -8

    so y = -8x +c

    -6 = -8 +c => c = 2

    y = -8x +2

    (9)

    Use implicit differentiation to find the slope of the tangent line to the curve:

    3x^2 -3xy +3y^3 = -192 at the point (-4,-4)

    6x -3xy' -3y +9y'y^2 = 0 but y' = m at given point

    6(-4) -3(-4)m -3(-4) +9m(-4)^2 = 0

    -24 +12m +12 +9*16m = 0

    -2 + m +1 +12m = 0

    m = 1/13

    2 days ago - 2

Still have questions? Get your answers by asking now.