Chapter 7: Problem 9
For each function, evaluate the given expression. \(f(x, y)=\sqrt{99-x^{2}-y^{2}}\), find \(f(3,-9)\)
Short Answer
Expert verified
The value of \( f(3, -9) \) is 3.
Step by step solution
01
Function Substitution Setup
The given function is \( f(x,y) = \sqrt{99-x^2-y^2} \). We need to find \( f(3, -9) \). This involves substituting \( x = 3 \) and \( y = -9 \) into the function.
02
Substitute the Values
Substitute \( x = 3 \) and \( y = -9 \) into the expression inside the square root: \( 99 - 3^2 - (-9)^2 \).
03
Calculate Squares
Calculate \( 3^2 \) which is 9 and \( (-9)^2 \) which is 81. So, the expression becomes \( 99 - 9 - 81 \).
04
Simplify the Expression
Simplify the inside of the square root: \( 99 - 9 - 81 = 9 \).
05
Compute the Square Root
Take the square root of 9, which is 3.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Evaluation
Function evaluation is a fundamental concept in calculus and algebra.It involves finding the output of a function given specific input values.In this exercise, we evaluated the function \( f(x, y) = \sqrt{99 - x^2 - y^2} \) by substituting \( x = 3 \) and \( y = -9 \).To effectively evaluate functions:
By mastering function evaluation, students can confidently tackle various mathematical challenges.
- Identify the given function and its variables.
- Substitute the provided values into the function.
- Perform any necessary calculations to simplify the expression.
- Compute to find the final result.
By mastering function evaluation, students can confidently tackle various mathematical challenges.
Step-by-Step Mathematical Solution
Solving mathematical problems by following step-by-step solutions can greatly simplify complex tasks.Breaking down the calculation of \( f(3, -9) \) into manageable steps makes it easier to follow.Let's revisit each stage of the solution for clarity.
- First, we substitute \( x = 3 \) and \( y = -9 \) into the function \( \sqrt{99 - x^2 - y^2} \).
- Next, we replace \( x\) and \( y\) in the expression: \( 99 - 3^2 - (-9)^2 \).
- We then calculate \( 3^2 \) which is 9, and \((-9)^2\) which is 81.
- The expression simplifies to \( 99 - 9 - 81 \).
- We simplify further to find it equals 9.
Square Root Calculation
Calculating the square root is a key part of many mathematical solutions, including this exercise.It involves finding a number which, when multiplied by itself, gives the original number.In this problem, after simplifying the expression to 9, we compute the square root.To understand square root calculations:
- Acknowledge that the square root of a number \( a \), denoted as \( \sqrt{a} \), is a value \( b \) such that \( b^2 = a \).
- For positive numbers like 9, the square root is straightforward: \( \sqrt{9} = 3 \), because \( 3 \times 3 = 9 \).
- Be cautious with perfect squares and familiar numbers for quick recall.