# Minima Maxima: 9a³y=x(4a-x)³

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

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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

- Log in to post comments

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## I think something is wrong

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=aand solve fory$9a^2 y = a(4a + a)^3$

$9a^2 y = 125a^4$

$y = \dfrac{125a^2}{9}$ ← not equal to 3

aKindly check the given.

## Ay sorry po.

In reply to I think something is wrong by Jhun Vert

## The same error. You can

In reply to Ay sorry po. by Francis June E…

The same error. You can evaluate if

x=a,y= 3a^{2}not 3a. Either the given is wrong or the answer key is wrong.## Kinuha ko kasi sa libro ni

In reply to The same error. You can by Jhun Vert

## i-check ko. Anong page?

In reply to Kinuha ko kasi sa libro ni by Francis June E…

i-check ko. Anong page?

## 62-64 sir

In reply to i-check ko. Anong page? by Jhun Vert

## Okay I got it. The given is

In reply to i-check ko. Anong page? by Jhun Vert

## May answer key po ba kayo

In reply to i-check ko. Anong page? by Jhun Vert

.

## $9a^3 y = x(4a - x)^3$

yin terms ofxusing 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 $9a^3 y'' = -4(4a - x)^2 - 8(4a - x)(a - x)$ $9a^3 y'' = -4(4a - x)[ (4a - x) + 2(a - x) ]$ $9a^3 y'' = -4(4a - x)(6a - 3x)$ $9a^3 y'' = -12(4a - x)(2a - x)$ Sety'to zero for maxima and/or minima $0 = 4(4a - x)^2 (a - x)$ For (4a-x)2 = 0:a, 0) is neither maximum nor minimuma-x= 0a, 0) is maximum.a= 1## Maraming Salamat po sir.

In reply to $9a^3 y = x(4a - x)^3$ by Jhun Vert

## Sir? Paano po naging (4a-4x)

## Okay na po pala sir hehe.

## May answer key po ba kayo

1

## y=x³-3x+1 Soln:

y=x³-3x+1

Soln: