The speaker that has a regular price of $90 is on sale for Cyber Monday Amazon with 30% off. What is the sale price with 6% tax?
1 answer:
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Answer:
b. 4x^2 + 3x - 6
Step-by-step explanation:
The values of f(x) for the extremes of x are more positive than the value of f(x) for the middle x, so we know the parabola opens upward. That eliminates choice D.
It is probably easiest to evaluate the other expressions to see which one matches the given f(x) values. For the purpose, it is usually easier to use the Horner form of the equation.
a. f(-2) = (3(-2) +4)(-2) -6 = -2(-2) -6 = -2 ≠ 4
b. f(-2) = (4(-2) +3)(-2) -6 = -5(-2) -6 = 4 . . . . matches the given data point
c. Because (b) matches, we know this one will not.
The appropriate choice is B.
