Q. \(2:x = x:50\). What one number can replace \(x\)?
Answer
Convert to fractions: \( \frac{2}{x} = \frac{x}{50} \). Cross-multiply: \(2\cdot 50 = x^2\), so \(x^2 = 100\). Thus \(x = \pm 10\). One number that can replace x is 10.
Detailed Explanation
Step-by-step solution
-
Write the proportion as an equation of fractions:
\[
\frac{2}{x} = \frac{x}{50}
\] -
Use cross-multiplication (multiply both sides by x and by 50) to eliminate denominators and obtain a polynomial equation. Multiplying both sides by \(x\cdot 50\) gives:
\[
2 \cdot 50 = x \cdot x
\]
which simplifies to
\[
100 = x^{2}
\] -
Solve the quadratic equation by taking square roots of both sides. The equation \(x^{2} = 100\) yields two real solutions:
\[
x = \sqrt{100} \quad \text{or} \quad x = -\sqrt{100}
\]
so
\[
x = 10 \quad \text{or} \quad x = -10
\] - Interpret the solutions: both \(x = 10\) and \(x = -10\) satisfy the algebraic equation. If the context requires a positive quantity (for example, a length or a positive ratio), choose the positive solution \(x = 10\). Otherwise both values are valid solutions to the given proportion.
Answer: x = 10 or x = -10. The one positive number that can replace x is 10.
See full solution
FAQs
What value(s) of x satisfy \( \frac{2}{x} = \frac{x}{50} \)?
Solve \( \frac{2}{x}=\frac{x}{50} \). Cross-multiply: \(2\cdot50 = x^2\), so \(x^2=100\). Thus \(x=10\) or \(x=-10\). If only one (positive) number is wanted, choose 10.
Why can't \(x=0\) be a solution?
\(x\) cannot be 0 because the equation has \(x\) in a denominator. Division by zero is undefined, so \(x=0\) is excluded from the domain.
How do you use cross-multiplication to solve \( \frac{2}{x}=\frac{x}{50} \)?
Cross-multiply to get \(2 \cdot 50 = x \cdot x\), i.e., \(100 = x^2\). Then take square roots: \(x = \pm\sqrt{100} = \pm 10\).
Are both \(+10\) and \(-10\) valid solutions?
Yes. Plugging in \(x=10\) gives \(2/10=10/50=0.2\). Plugging in \(x=-10\) gives \(2/(-10)=(-10)/50=-0.2\). Both satisfy the equation.
If the problem asks for "one number" to replace \(x\), which should you give?
Usually give the positive root \(x=10\) unless negatives are allowed or specifically requested. Many contexts mean the principal (positive) solution.
How is \(x\) related to 2 and 50 in terms of means?
How is \(x\) related to 2 and 50 in terms of means?
How can you quickly check your answers?
Substitute back into \( \frac{2}{x}=\frac{x}{50} \). For \(x=10\): \(2/10=10/50\). For \(x=-10\): \(2/(-10)=(-10)/50\). Both sides match, so the answers are correct.
Could there be complex solutions to \( \frac{2}{x}=\frac{x}{50} \)?
From \(x^2=100\), the only solutions are \(x=\pm10\), which are real. No additional complex solutions arise because the polynomial is degree 2 with real roots ±10.
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