Question

What is the value of the expression when a = 3 and b = 2?

3a^3 + 2b^3
--
A. 78
B. 97
C. 135
D. 745

Please don't respond with the answer alone, I'd like to know how to work through it. :)

Answer 1

3a³ + 2b³ = ?

Substitute for values:

3a³ + 2b³
a = 3
3 × 3³ + 2b³

b = 2
3a³ + 2 × 2³

Full question:

3 × 3³ + 2 × 2³

3 × 3³ + 2 × 2³
3 × 27 + 2 × 2³
3 × 27 + 2 × 8
81 + 16
97

The value of the expression 3a³ + 2b³ when a = 3 and b = 2 is 97.

3 × 3³ + 2 × 2³ = 97