A closed box is constructed of 4200cm2 of cardboard. The box is a cuboid, with height hcm and square base of side xcm . What is the value of x which maximises the volume of the box? Give your answer in cm correct to 3 significant figures. [Answer format: 00.0 cm]

x is 10

Step-by-step explanation:

Given that:

<=> 2 + 4xh = 4200 cm2

<=> 4xh = 4200 - 2  

<=> h = (4200 - 2  )/4x

V =  h

<=> V =  (4200 - 2  )/4x

<=> V = (4200x - 2 )/4

dV/dx = (4200 - 6 )/4

Set dV/dx = 0, we have:

4200 - 6 =0

<=>  = 700

<=> x = 10

d²V/dx² =  -12x/4

It is negative so the volume is maximum.

So x is 10

93.8

step-by-step explanation:

lets say, first number = x

second number = 3x+7

total = 49

(x)+(3x+7)= 49

4x+7 = 49

4x = 42

x = 42/4

x= 10.5

x= 10.5

3x+7 = 3(10.5)+7 = 93.8

hope this

15 units use socratic

step-by-step explanation: 15 units