Question

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

Answer 1

-3(2)^2 +1^3 + 3(3)^2 – 2(-1)^3

Answer 2

^ ok, you've plugged in the numbers correctly, all you have to do is calculate what that expression is equal to...

Answer 3

I got 14 but I dont know if its correct

Answer 4

well, let's take it step by step:

-3(2)^2 = ?

Answer 5

-6^2 or -3(4)?

Answer 6

it's -3(4)

remember, the exponent only applies to the number next to it

Answer 7

Okay -3(4)

Answer 8

1^3 = ?

Answer 9

1

Answer 10

good.

3(3)^2 = ?

(again, remember that the exponent only applies to the number next to it)

Answer 11

3(9)

Answer 12

good,

– 2(-1)^3 = ?

Answer 13

Above, why would the 1 be positive if it was negative in the equation?

Answer 14

-2(-1)

Answer 15

if b = -1

then -b^3 = -(-1)(-1)(-1) = 1

Answer 16

Ohhhhhh. Okay I get it. Gotcha. Okay continue (:

Answer 17

and yes, – 2(-1)^3 = -1

so we put everything together:

-3(2)^2 +1^3 + 3(3)^2 – 2(-1)^3

= -3(4) + 1 + 3(9) -2(-1)

can you take over from here?

Answer 18

g2g but the final answer should be 18

Answer 19

Got it. Thank you so much