Question

A pyramid has a rectangular base of length (3x + 1)cm and width xcm.

Answer 1

Answer:

The dimension of the base of the Rectangle Pyramid is Length = 10 and Width = 8/3

Step-by-step explanation:

Given

Rectangle Pyramid

Base Length = 3x + 1

Base Width = x

Height = 12

Volume = 96

Required

Dimension of the base of the pyramid

Given that the volume of the pyramid is ⅓ of the base area * the height.

This is represented mathematical as

Volume = ⅓ * base area * height.

Where

Base area = width * length

Base area = (3x + 1) * x

Base area = 3x² + x.

So,

Volume becomes

Volume = ⅓ * (3x² + x) * 12.

Volume = (3x² + x) * 4

Substitute 96 for volume

96 = (3x² + x) * 4

Divide both sides by 4

96/4 = (3x² + x) * 4/4

24 = 3x² + x

Subtract 24 fr both sides

24 - 24 = 3x² + x - 24

0 = 3x² + x - 24

3x² + x - 24 = 0

Expand

3x² + 9x - 8x - 24 = 0

Factorize

3x(x + 3) - 8(x + 3) = 0

(3x - 8)(x + 3) = 0

3x - 8 = 0 or x + 3 = 0

3x = 8 or x = -3

x = 8/3 or x = -3

Recall that

Length = 3x + 1

Width = x

For any of the above expression, x can't be less than 0; so, x = -3 can't be considered.

Substitute x = 8/3

Length = 3x + 1

Length = 3(8/3) + 1

Length = 8 + 1

Length = 9

Width = x

Width = 8/3

Hence, the dimension of the base of the Rectangle Pyramid is Length = 10 and Width = 8/3