Patulong po ulit ako mam/sir Yung process po sana ulit 9a²y=x(4a+x)³ Yung ans nya po is (a,3a) maximum Thanks in advance mam/sir
I think something is wrong with your given. If you check for x = a, y ≠ 3a. Here is the checking of your answer key.
Set x = a and solve for y $9a^2 y = a(4a + a)^3$
$9a^2 y = 125a^4$
$y = \dfrac{125a^2}{9}$ ← not equal to 3a
Kindly check the given.
Ay sorry po. Eto po sir 9a²y=x(4a-x)³
The same error. You can evaluate if x = a, y = 3a2 not 3a. Either the given is wrong or the answer key is wrong.
Kinuha ko kasi sa libro ni Love and Rainville yang example sir.
i-check ko. Anong page?
62-64 sir
Okay I got it. The given is actually $9a^3 y = x(4a - x)^3$
.
$9a^3 y = x(4a - x)^3$
Differentiate y in terms of x using product formula $9a^3 y' = -3x(4a - x)^2 + (4a - x)^3$
Simplify (optional) $9a^3 y' = (4a - x)^2 [-3x + (4a - x)]$
$9a^3 y' = (4a - x)^2 (4a - 4x)$
$9a^3 y' = 4(4a - x)^2 (a - x)$
Determine the 2nd derivative $9a^3 y'' = -4(4a - x)^2 - 8(4a - x)(a - x)$
$9a^3 y'' = -4(4a - x)[ (4a - x) + 2(a - x) ]$
$9a^3 y'' = -4(4a - x)(6a - 3x)$
$9a^3 y'' = -12(4a - x)(2a - x)$
Set y' to zero for maxima and/or minima $0 = 4(4a - x)^2 (a - x)$
For (4a - x)2 = 0:
$9a^3 y = 4a(4a - 4a)^3$
$y = 0$
Check if Maxima or Minima. $9a^3 y'' = -12(4a - 4a)(2a - 4a)$
$y'' = 0$ ← inflection point (the curve is neither upward nor downward)
Hence, (4a, 0) is neither maximum nor minimum
For a - x = 0
$9a^3 y = a(4a - a)^3$
$y = 3a$
Check if Maxima or Minima. $9a^3 y'' = -12(4a - a)(2a - a)$
$y'' = (-)$ ← the curve is concave downward
Hence, (a, 0) is maximum.
Here is the graph of the curve with a = 1
Maraming Salamat po sir. Godbless you po. :)
Sir? Paano po naging (4a-4x) ? Yung sa simplify po
Okay na po pala sir hehe. Salamat po
1
y=x³-3x+1 Soln:
More information about text formats
Follow @iMATHalino
MATHalino
I think something is wrong with your given. If you check for x = a, y ≠ 3a. Here is the checking of your answer key.
Set x = a and solve for y
$9a^2 y = a(4a + a)^3$
$9a^2 y = 125a^4$
$y = \dfrac{125a^2}{9}$ ← not equal to 3a
Kindly check the given.
Ay sorry po.
Eto po sir 9a²y=x(4a-x)³
The same error. You can evaluate if x = a, y = 3a2 not 3a. Either the given is wrong or the answer key is wrong.
Kinuha ko kasi sa libro ni Love and Rainville yang example sir.
i-check ko. Anong page?
62-64 sir
Okay I got it. The given is actually $9a^3 y = x(4a - x)^3$
.
$9a^3 y = x(4a - x)^3$
Differentiate y in terms of x using product formula
$9a^3 y' = -3x(4a - x)^2 + (4a - x)^3$
Simplify (optional)
$9a^3 y' = (4a - x)^2 [-3x + (4a - x)]$
$9a^3 y' = (4a - x)^2 (4a - 4x)$
$9a^3 y' = 4(4a - x)^2 (a - x)$
Determine the 2nd derivative
$9a^3 y'' = -4(4a - x)^2 - 8(4a - x)(a - x)$
$9a^3 y'' = -4(4a - x)[ (4a - x) + 2(a - x) ]$
$9a^3 y'' = -4(4a - x)(6a - 3x)$
$9a^3 y'' = -12(4a - x)(2a - x)$
Set y' to zero for maxima and/or minima
$0 = 4(4a - x)^2 (a - x)$
For (4a - x)2 = 0:
$9a^3 y = 4a(4a - 4a)^3$
$y = 0$
Check if Maxima or Minima.
$9a^3 y'' = -12(4a - 4a)(2a - 4a)$
$y'' = 0$ ← inflection point (the curve is neither upward nor downward)
Hence, (4a, 0) is neither maximum nor minimum
For a - x = 0
$9a^3 y = a(4a - a)^3$
$y = 3a$
Check if Maxima or Minima.
$9a^3 y'' = -12(4a - a)(2a - a)$
$y'' = (-)$ ← the curve is concave downward
Hence, (a, 0) is maximum.
Here is the graph of the curve with a = 1
Maraming Salamat po sir. Godbless you po. :)
Sir? Paano po naging (4a-4x) ? Yung sa simplify po
Okay na po pala sir hehe. Salamat po
1
y=x³-3x+1
Soln:
Add new comment