What dose f (x) = 3-x; g (x) = - 2x equal

Which two equations represent the same function?

A) y = 2x - 7 and f (x) = 7 - 2x

B) 3x = y - 2 and f (x) = 3x - 2

C) f (x) = 3x2 + 5 and y = 3x2 + 5

D) None of the above

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A) y = 2x - 7 and f (x) = 7 - 2x

Incorrect. These equations look similar but are not the same. The first has a slope of 2 and a y-intercept of - 7. The second function has a slope of - 2 and a y-intercept of 7. It slopes in the opposite direction. They do not produce the same graph, so they are not the same function. The correct answer is f (x) = 3x2 + 5 and y = 3x2 + 5.

B) 3x = y - 2 and f (x) = 3x - 2

Incorrect. These equations represent two different functions. If you rewrite the first equation in terms of y, you’ll find the equation of the function is y = 3 x + 2. The correct answer is f (x) = 3x2 + 5 and y = 3x2 + 5.

C) f (x) = 3x2 + 5 and y = 3x2 + 5

Correct. The expressions that follow f (x) = and y = are the same, so these are two different ways to write the same function: f (x) = 3x2 + 5 and y = 3x2 + 5. D) None of the above

Incorrect. Look at the expressions that follow f (x) = and y =. If the expressions are the same, then the equations represent the same exact function. The correct answer is f (x) = 3x2 + 5 and y = 3x2 + 5.