Chapter 8: Problem 10
Determine whether each ordered pair is a solution of the system of equations. $$\left\\{\begin{aligned} -\log _{10} x+3 &=y \\ \frac{1}{9} x+y &=\frac{28}{9} \end{aligned}\right.$$ (a) (100,1) (b) (10,2) (c) (1,3) (d) (1,1)
Short Answer
Expert verified
Of the given ordered pairs, only (1,3) is a solution to the system of equations.
Step by step solution
01
Analyze the System of Equations
The provided system contains two equations: \(-\log_{10}x+3 = y\) and \(\frac{1}{9}x+y = \frac{28}{9}\). They are to be checked for certain ordered pairs (x, y). Remember that logarithm is the reverse process of exponentiation; hence \(-\log_{10} 100 = -2, -\log_{10}10 = -1, -\log_{10}1 = 0 \). Now, replace each pair into both equations to see if they yield true statements.
02
Check Pair (100,1)
Substitute x=100, y=1 into the two equations. For the first equation, you get \(-\log_{10} 100 + 3 = -2 + 3 =1 \), which matches the y value of 1. For the second equation, you get \(\frac{1}{9}*100 + 1 = \frac{28}{9}\) which simplifies to \(\frac{100}{9} + 1 \neq \frac{28}{9}\), which is not true. Hence, (100,1) is not a solution.
03
Check Pair (10,2)
Substitute x=10, y=2 into the two equations. For the first equation, you end up with \(-\log_{10}10 + 3 = -1 + 3 = 2 \), which matches the y value of 2. For the second equation, you get \(\frac{1}{9}*10 + 2 = \frac{28}{9}\), which simplifies to \(\frac{10}{9} + 2 \neq \frac{28}{9}\), which is untrue. Hence, (10,2) is not a solution.
04
Check pair (1,3)
Substitute x=1, y=3 into the equations. For the first equation, you get \(-\log_{10}1+3 = 0 + 3 = 3\), which aligns with the y value of 3. In the second equation, you get \(\frac{1}{9}*1 + 3 = \frac{28}{9}\), which simplifies to \(\frac{1}{9} + 3 = \frac{28}{9}\). This is a true statement. Hence, (1,3) is a solution.
05
Check pair (1,1)
Substitute x=1, y=1 into the equations. For the first equation, you end up with \(-\log_{10}1 + 3 = 0 + 3 = 3\), which does not match the y value. Hence, (1,1) is not a solution.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Logarithmic Functions
Logarithms are a fundamental concept in algebra and calculus, often cropping up in equations where the variable is an exponent. A logarithmic function, like those in our exercise, acts as the inverse of an exponential function. In simpler terms, it helps us determine what exponent we need to get a certain result.
In the expression \(-\log_{10}x\), the logarithm calculates the power to which 10 must be raised to result in \(x\). For example:
In the expression \(-\log_{10}x\), the logarithm calculates the power to which 10 must be raised to result in \(x\). For example:
- \(-\log_{10} 100\) yields \(-2\), since 10 squared equals 100.
- \(-\log_{10} 10\) yields \(-1\), as 10 to the power of 1 is 10.
- \(-\log_{10} 1\) equals 0, because 10 to the power of 0 equals 1.
Ordered Pairs
Ordered pairs represent solutions to systems of equations and consist of two elements: \(x\) and \(y\), usually written as \(x, y\). Each pair suggests a potential solution that could satisfy both equations in our system.
When determining if a pair such as (100,1) is a solution:
When determining if a pair such as (100,1) is a solution:
- First check both values in the system's first equation.
- Next verify the pair in the second equation of the system.
- If both equations hold true for the same pair, then it is a solution of the system.
Solution Verification
Verifying solutions in a system of equations is crucial to finding accurate results. This involves checking whether given ordered pairs make both equations true.
Here is a simple process to perform solution verification:
Here is a simple process to perform solution verification:
- Substitute the \(x\) and \(y\) values of the ordered pair into the first equation.
- Examine the outcome to see if it matches the result expected in the equation.
- Repeat this for the second equation using the same values of \(x\) and \(y\).
- If both verifications result in true statements, the ordered pair satisfies the system.
Algebraic Substitution
Algebraic substitution is a straightforward yet powerful technique wherein you replace a variable with its equivalent numerical value or expression.
To apply substitution effectively:
To apply substitution effectively:
- Identify the variable you need to substitute, often given directly in the ordered pair \((x, y)\).
- Replace \(x\) or \(y\) in the equation with its specific value from the pair.
- Solve the equation to see if it stands true with these replacements.