Chapter 1: Problem 33
Solve each equation. Check each result. See Example 3. $$ -\frac{4}{5} s=2 $$
Short Answer
Expert verified
The solution is \(s = -\frac{5}{2}\).
Step by step solution
01
Isolate the variable
The equation is given as \(-\frac{4}{5} s = 2\). To solve for \(s\), we need to isolate \(s\). We can do this by multiplying both sides of the equation by the reciprocal of \(-\frac{4}{5}\), which is \(-\frac{5}{4}\). This gives us:\[s = 2 \times \left(-\frac{5}{4}\right)\].
02
Simplify the equation
Now, let's simplify the equation. Multiply \(2\) by \(-\frac{5}{4}\): \[s = -\frac{10}{4}\].
03
Further simplify the fraction
To simplify \(-\frac{10}{4}\), find the greatest common divisor of 10 and 4, which is 2. Divide both numerator and denominator by 2: \[s = -\frac{5}{2}\].
04
Check the result
To check if \(s = -\frac{5}{2}\) is correct, substitute \(s\) back into the original equation: \(-\frac{4}{5} \times -\frac{5}{2} = 2\). Multiplying gives \(\frac{20}{10} = 2\), which simplifies to \(2 = 2\). Since both sides of the equation are equal, our solution is verified.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Isolate the Variable
When solving linear equations, a key goal is to isolate the variable—basically, to get the variable on one side of the equation by itself. Let's say you have an equation that's a bit more complicated, like \(-\frac{4}{5} s = 2\). The idea is to "clear out" the coefficients or fractions that are sticking around with the variable. This often involves performing the same operation on both sides of the equation.
- Identify what's sticking to your variable. Here, it's \-\frac{4}{5}\.
- Think about what you can do to "undo" those numbers. Opposite operations help to cancel them out.
- If it's being multiplied, divide. If it's being divided, multiply. Here, you'd multiply by the reciprocal of \-\frac{4}{5}\.
Reciprocal
The reciprocal of a number is essentially what you flip to get a rate of \(1\). For any non-zero fraction \(\frac{a}{b}\), its reciprocal is \(\frac{b}{a}\). When they are multiplied together, they equal one: \(\frac{a}{b} \times \frac{b}{a} = 1\).
Why is this important? Because the reciprocal helps us isolate the variable by cancelling coefficients out:
Why is this important? Because the reciprocal helps us isolate the variable by cancelling coefficients out:
- If you multiply a term by its reciprocal, you get \(1\), effectively removing it from the equation.
- For \-\frac{4}{5} s = 2\, multiply both sides by the reciprocal \-\frac{5}{4}\ to remove \-\frac{4}{5}\ from \(s\).
Simplifying Fractions
Once you've used the reciprocal to isolate the variable, you might end up with a fraction that could be simpler. Simplifying fractions makes your answer neat and easy to understand. Let's consider the resulting fraction in our equation: \-\frac{10}{4}\.
To simplify a fraction:
To simplify a fraction:
- Find the greatest common divisor (GCD) of the numerator and the denominator.
- Divide both by this GCD; here, divisible by \(2\).
- \(\frac{10}{4} = \frac{5}{2}\) once simplified.