Question

Find -3a2 - b3 + 3c2 - 2b3 if a = 2, b = -1, and c = 3.

Answer 1

\(-3a^2 - b^3 + 3c^2 - 2b^3\)

\(-3(2)^2 + 1^3 + 3(3)^2 - 2(-1)^3\)

Can you simplify that?

Answer 2

Possibly.

Answer 3

Okay, first we do the exponents.

\(\sf(2)^2, (3)^2~and~(-1)^3\)

Answer 4

Ok

Answer 5

2^2 = ?
3^2 = ?
-1^3 = ?

Simplify those

Answer 6

I don't know that.

Answer 7

\(2^2 \rightarrow 2 \times 2\)
\(3^2 \rightarrow 3 \times 3\)
\(-1^3 \rightarrow -1 \times -1 \times -1\)

Answer 8

-3(2)^2 + 1^3 + 3(3)^2 - 2(-1)^3
Use PEMDAS.
Parentheses:
-3(2) = -6
3(3) = 9
2(-1) = -2
Put them in.
-6^2 + 1^3 + 9^2 + 2^3

Answer 9

Now Exponents.
-6^2 + 1^3 + 9^2 + 2^3
-6^2 = 36
1^3 = 1
9^2 = 81
2^3 = 8
Put them in.
36 + 1 + 81 + 8

Answer 10

36 + 1 + 81 + 8
Now just add.
36 + 1 = 37
81 + 8 = 89
37 + 89 = 126

Answer 11

Does that help?