Algbrea 2 Math

Question

A cube has a surface area of 6x^2+48x+96.  Find the length of the side?

Answer 1

Let SA=surface area and a=side length of a cube.   The surface area of a cube is 6a^2. 

SA=6a^2 and SA=6x^2+48x+96

We must solve for a to find the length of a side.

1. 6a^2=6x^2+48x+96.

2. Factor 6; 6(a^2)=6(x^2+8X+16)   DIVIDE BY 6

3. a^2=x^2+8x+16

4. a^2=(x+4)(x+4)=(x+4)^2

5. square root of a^2=a; square root of (x+4)^2=(x+4)

6.a=x+4

 

Answer 2

Hey David -- since cubes, like dice, are each 6-sided => one face A is x^2 +8x +16 ...

 

==> A = (x+4)^2 means side length is x+4 ... Best wishes, sir :)