Question 647·Easy·Algebra

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The function $p$ is defined by $p(x)=\dfrac{5x}{2}+6$ . What is the value of $p(4)$ ?

In function notation, the number inside parentheses is the input, and the function's value is the output. To find a value at a given input, replace the rule's variable with that number. In Desmos, define the function, then type the requested value on the next line. Don't mistake a number inside the rule for the input.

Hints

Hint 1
In function notation, $p(4)$ tells you the input is $4$ . Replace $x$ with $4$ in the rule. Which numbers in the rule stay the same?
Hint 2
A fraction bar shows what gets divided: here, $5x$ is divided by $2$ , and then $6$ is added. Keep the added term outside the fraction when you type the rule.

Step-by-step

Substitute the input and evaluate
Step 1
Put the input into the rule
In function notation, $p(4)$ makes $4$ the input, so replace $x$ with $4$ :
$p(4)=\frac{5(4)}{2}+6.$
Only $x$ changes; the $2$ under the fraction bar stays $2$ .
Step 2
Define the function in Desmos
Type $p(x)=\frac{5x}{2}+6$ in Desmos. It stores the function rule under the name $p$ , so you can give it the input on the next line. Keep $+6$ outside the fraction.
Step 3
Read the output
Type $p(4)$ on the next line. Desmos shows $p(4)=16$ , so the output for input $4$ is $16$ . Choice C.

Question 647·Easy·Algebra

Strategy

Hints

Step-by-step

Lessons that teach this

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Strategy

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Step-by-step

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