I don't understand this question or how to do it please help. Algebra 1

Question

The dimensions of a box are as follows:

width = x

length = x + 2

height = 3x

Part 1: Write an expression that represents the volume of the box in cubic units. v=lwh

Part 2: Show your work that simplifies the expression that represents the volume of the box.

Part 3: Write an expression that represents the surface area of the box in square units. sa=2(wl+hl+hw)

Part 4: Show your work that simplifies the expression that represents the surface area of the box. 

Answer 1

width = w = x

length = l = x + 2

height = h = 3x

Part 1: Write an expression that represents the volume of the box in cubic units. v=lwh

v = volume

= l * w * h

= x * (x + 2) * 3x

Part 2: Simplified v is:

v = x * (x + 2) * 3x

= 3x^2 (x + 2)

= 3x^3 + 6x^2

Part 3: Write an expression that represents the surface area of the box in square units. sa=2(wl+hl+hw)

sa = surface area

= 2 * (wl + hl + hw)

= 2 * ((x + 2) * x) + (3x * x) + (3x * (x + 2))

Part 4: Simplified sa is: 

sa = 2 * ((x + 2) * x) + (3x * x) + (3x * (x + 2))

= 2 * (x^2 + 2x + 3x^2 + 3x^2 + 6x)

= 2 * (7x^2 + 8x)

= 14x^2 +16x

Answer 2

The volume of a box can be found by multiplying the length times width times height. However, the dimensions of your box are all in terms of x, therefore the formula (or expression) that represents the volume of the box will be as follows:

width = x

length = x + 2

height = 3x

Part 1

Plug the variables into the below equation

V = width * length * height = (x) * (x+2) * (3x)

Part 2

Now simplify the equation using order of operations and grouping like terms

V = x(x+2)(3x) = 3x²(x+2) = 3x³ + 6x²

Doublecheck your answer. If x = 1

V = width * length * height = (x) * (x+2) * (3x) = (1) * (1+2) * (3*1) = 1 * 3 * 3 = 9

Simplified formula

V = 3x³ + 6x² = 3(1)³+6(1)²= 3 + 6 = 9

Part 3

width = x

length = x + 2

height = 3x

Plug the variables into the below equation

SA = 2 (width * length + height * length + height * width)

SA = 2 (x * (x + 2) + 3x * (x+2) + 3x * x )

Part 4

Now simplify the equation using order of operations and grouping like terms

SA = 2 ( x(x+2) + 3x(x+2) + 3x(x) )

SA = 2 ( x²+ 2x + 3x² + 6x + 3x² )

Group like terms

SA = 2 ( x² + 3x² + 3x² + 2x + 6x)

Simplify

SA = 2 (7x² + 8x) = 14x² + 16x

Doublecheck your answer, if x = 1

SA = 2 (x * (x + 2) + 3x * (x+2) + 3x * x ) = 2( 1(1+2) + 3(1)*(1+2) + 3*1*1) = 2( 3 + 9 + 3) = 30

Simplified formula

SA = 14x² + 16x = 14 *1² + 16*1 = 30