Chapter 3: Problem 84
For Problems \(69-84\), solve each of the equations. $$ -5 a=-a^{2} $$
Short Answer
Expert verified
The solutions are \(a = 0\) and \(a = 5\).
Step by step solution
01
Rearrange the equation
The given equation is \(-5a = -a^2\). Begin by rearranging all terms to one side of the equation to set it equal to zero. Add \(a^2\) to both sides: \(a^2 - 5a = 0\).
02
Factor the equation
Factor the expression on the left side of the equation. Find the greatest common factor of the terms: \(a(a - 5) = 0\).
03
Solve each factor
Set each factor equal to zero and solve for \(a\). For \(a = 0\), the solution is \(a = 0\). For \(a - 5 = 0\), solve to get \(a = 5\).
04
Compile the solutions
The solutions to the equation are the values of \(a\) that satisfy both factors. Hence, the solutions are \(a = 0\) and \(a = 5\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Factoring
Factoring is a crucial step in solving quadratic equations, including those of the form seen in our exercise. When we factor, we are essentially breaking down a complex expression into simpler components, or "factors," that multiply to give the original expression. This is similar to finding the prime factors of a number, but here, it’s for algebraic expressions. In the equation \(a^2 - 5a = 0\), our goal is to factor out the greatest common factor (GCF) from the terms.
- The terms \(a^2\) and \(-5a\) share a common factor, which is \(a\).
- By factoring out \(a\), the expression becomes \(a(a - 5) = 0\).
Solving Equations
Solving equations involves finding the values of the variables that make the equation true. In our quadratic equation case, the solution process involves using the factored form \(a(a - 5) = 0\). The zero-product property is a fundamental principle used here, stating that if a product of two factors equals zero, at least one of the factors must be zero.
- First, set each factor equal to zero: \(a = 0\) and \(a - 5 = 0\).
- Solving \(a = 0\) gives us a direct solution: \(a = 0\).
- For \(a - 5 = 0\), add 5 to both sides to isolate \(a\), yielding \(a = 5\).
Algebraic Expressions
Algebraic expressions are like the building blocks of equations. They consist of numbers, variables, and operations that define a mathematical phrase. In our problem, the expression \(-5a = -a^2\) is manipulated to solve the equation using algebraic principles. When dealing with such expressions:
- Combine like terms: Start by rearranging terms to one side to simplify further actions, seen here as bringing all terms to equal zero.
- Simplification: Reducing expressions helps make the factorization process easier, as done when transforming the equation to \(a^2 - 5a = 0\).
- Utilizing properties: Recognizing when to apply properties like the zero-product property aids in efficient problem-solving.