Question

When b greater than or equal to zero, 12a^2b^3 – a^6 – b^9
a) always is less than or equal to 64
b) always negative
c) always greater than 64
d) always lies in the internal [60,64]

Answer 1

what about a?

Answer 2

The answer must be A. I will disprove all others, leaving only A.

B .. a = 0, b = 0, so the equation =0, which is NOT negative, so B is wrong.

C .. Same case as B. 0 is less than 64, so C is wrong.

D .. Same case as B and C haha. 0 is not in that interval.

Answer 3

The value of "a" is unknown. It was not given in the question.

Answer 4

ah so good @mathandphysics

Answer 5

thanks for medal :)

Answer 6

U r welcome.

Answer 7

Also, you knew it couldn't be B because all negative numbers are also encompassed in part A, so if B was right, A would automatically be right also. Just a side-note.