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27 votes
27 votes
Let f(x)=4x2−5x+9. What is the value of f(−5)?

Group of answer choices

28

-66

43

134

User Saunderl
by
2.6k points

1 Answer

16 votes
16 votes

Answer:

f(-5) = 134

Explanation:

f(x) = 4x² - 5x + 9

f(anything) will set the value of x to the value thats in f(x).

f(-5) = 4(-5)² - 5(-5) + 9

Square the -5. Remember, (-x)² = (-x) * (-x) = x²

f(-5) = 4(25) - 5(-5) + 9

Multiply 4 and 25, and -5 and -5.

f(-5) = 100 + 25 + 9

Add 25 and 100.

f(-5) = 125 + 9

Add 125 and 9.

f(-5) = 134.

User Klijakub
by
3.0k points