Answer:
- (a) no
- (b) yes
- (c) no
- (d) no
Step-by-step explanation:
"Of the order x^2" means the dominant behavior matches that of x^2 as x gets large. For polynomial functions, the dominant behavior is that of the highest-degree term.
For other functions, the dominant behavior will typically be governed in some other way. Here, the rate of growth of the x·log(x) function is determined by log(x), which has decreasing slope as x increases.
Only answer selection B has a highest-degree term of x^2, so only that one exhibits O(x^2) behavior.
This is known as Einstein's proof, not because he was the first to come up with it, but because he came up with it as a 15 year old boy.
Here the problem is justification step 2. The written equation
BC ÷ DC = BC ÷ AC
is incorrect, and wouldn't get us our statement 2, which is correct.
For similar triangles we have to carefully pair the corresponding parts to get our ratios right:
ABC ~ BDC means AB:BD = BC:DC = AC:BC so BC/DC=AC/BC.
Justification 2 has the final division upside down.
I think the correct answer is b 75
