Question

the charge \\(c\\), in mah, of a cell phone battery run at a rate of \\(r\\) ma is calculated using the function \\(c(r) = 450 - 18r\\), where \\(r\\) represents the rate of discharge.
what is the charge of the cell phone battery after 15 ma of discharge?

Explanation:

The image is quite blurry, but the text can be transcribed as follows:

Problem Statement:

"The height \(h\) in feet of a ball dropped from the top of a \(400\text{-foot}\) tall building can be described by the function \(h(t) = 400 - 16t^2\), where \(t\) represents the number of seconds after the ball is dropped.

What is the height of the ball \(4\) seconds after it is dropped?"

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⚡ Using what you learned: evaluating functions

Step 1: Identify the function and the input value

We are given the height function:

$$ h(t) = 400 - 16t^2 $$

We need to find the height of the ball at \( t = 4 \) seconds.

Step 2: Substitute \( t = 4 \) into the function

Substitute \( 4 \) for \( t \) in the equation:

$$ h(4) = 400 - 16(4)^2 $$

Step 3: Simplify the expression

First, calculate the exponent:

$$ 4^2 = 16 $$

Next, multiply:

$$ 16 \times 16 = 256 $$

Finally, subtract:

$$ h(4) = 400 - 256 = 144 $$

Answer:

144