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1 vote
Which of the following functions is graphed above?

f(x) = 4log(x + 4)


f(x) = -4log(x + 4)


f(x) = 4log(-x - 4)


f(x) = -4log(-x + 4)

Which of the following functions is graphed above? f(x) = 4log(x + 4) f(x) = -4log-example-1

2 Answers

4 votes
It's obvious from the graph that the x-intercept is (3,0). Thus, when x=3, y=0. We can use this fact to eliminate those of the 4 possible answers that could not be correct. Note that log (1) = 0.

Eliminate the first answer: log(x + 4). Why? Because when x=3,
log(x + 4)=log(3 + 4)= log 7, which is NOT zero.

Elim. the second answer for the same reason.

Next, look at the third answer: log(x + 4). If x=3, we get log(7), which is not zero.

That leaves only the fourth answer choice. But check that out also:

f(x) = -4log(-x + 4). When x=3, we get f(3)= -4log(-x + 4) = -4(log[1]) = 0. This is correct.
User Andriy Antonov
by
8.6k points
4 votes
That would be choice D
User Luc Hendriks
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7.0k points

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