Question

HELP ASAP Which points are on the graph of the function rule ƒ(x) = 10 – 4x?

a. (18, –2), (10, 0), (2, 2)

b. ( –18, 2), ( –10, 0), ( –2, –2)

c.(–2, 18), (0, 10), (2, 2)

d. (2, –18), (0, –10), ( –2, –2)

Answer 1

If f(x) = 10 - 4x...

f(18) = 10 - 4(18) = 10 - 72 = -62 ≠ -2

This rules out answer a, since (18,-62) would be a point, not (18,-2).

f(-18) = 10 - 4(-18) = 10 + 72 = 82 ≠ -2

This rules out answer b, since (-18,82) would be a point, not (-18,2).

f(-2) = 10 - 4(-2) = 10 + 8 = 18

Answer c seems to be ok so far, since (-2,18) is a point in answer c.

f(2) = 10 - 4(2) = 10 - 8 = 2 ≠ =18

This rules out answer d, since (2,2) would be a point, not (2,-18).

The only answer that wasn't ruled out by check the first point in each answer is answer C.