please help me with this!

The original area of a face would be a^2. Now that you added b to the edge, the new area of each face would be (a+b)^2. To find how much the are increased, subtract a^2 from (a+b)^2. [tex] (a+b)^2-(a^2)= a^2+2ab+b^2-(a^2)= 2ab+b^2= b(2a+b) [/tex] So the answer is b(2a+b)
Volume of the cube = a³ (Given)
[tex] \boxed{ \text{Volume of a cube = side}^3} [/tex]
Side of a cube = ∛a³ = a
Side of the cube after it increased by b = a + b
[tex] \boxed{\text{Area of a cube = side}^2} [/tex]
Area of the cube = (a + b)²
Increase in area = (a + b)² - a²
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Simplify (a + b)² - a²:
(a + b)² - a²
Open (a + b)² as a² + 2ab + b² :
= a² + 2ab + b² - a²
Combine a² and -a²:
= 2ab + b²
Take out b as the common factor:
= b(2a + b)
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Answer: (H) b(2a + b)