Question

For the function r, r(25)=1/2x²-3x, what is the value of f(9)?

a. 18
b. 32
c. -18
d. -32

Answer 1

The value of
`\( r(9) \)` for the given function
`\( r(x) = (1)/(2)x^2 - 3x \`) is -18. Therefore, the correct answer is option (c).

Step-by-step explanation

To find the value of
`\( r(9) \),` substitute
`\( x = 9 \)` into the given function
`\( r(x) = (1)/(2)x^2 - 3x \):`

`\[ r(9) = (1)/(2)(9)^2 - 3(9) \]`

`\[ r(9) = (1)/(2)(81) - 27 \]`

`\[ r(9) = 40.5 - 27 \]`

`\[ r(9) = -18 \]`

Therefore, the correct answer is -18, which corresponds to option (c).

The function
`\( r(x) = (1)/(2)x^2 - 3x \)` represents a quadratic function. The process of finding
`\( r(9) \)` involves substituting the value of
`\( x \)` (which is 9 in this case) into the function and performing the necessary calculations. The resulting value (-18) indicates the function's output when
`\( x = 9 \)`. This process is a fundamental concept in evaluating functions and is commonly used in mathematics to determine specific values based on given functions.