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Example 9.86 from Elementary Algebra, 9.6 Solve Equations with Square Roots
Solve Equations with Square Roots: example 9.86
Christy dropped her sunglasses from a bridge 400 feet above a river. Use the formula to find how many seconds it took for the sunglasses to reach the river.
Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.
Solution
Step 1. Read the problem. Step 2. Identify what you are looking for. The time it takes for the sunglasses to reach
the river.Step 3. Name what you are looking for by
choosing a variable to represent it.Let t = time. Step 4. Translate into an equation by writing the
appropriate formula or model for the situation.
Substitute in the given information.Step 5. Solve the equation using good algebra
techniques.Step 6. Check the answer in the problem and
make sure it makes sense.Does 5 seconds seem reasonable?
Yes.Step 7. Answer the question with a complete
sentence.It will take 5 seconds for the sunglasses to hit
the water.
Your turn
The book's Try It right after this example: same idea, new numbers. Only the answer is given.
A helicopter dropped a rescue package from a height of 1,296 feet. Use the formula to find how many seconds it took for the package to reach the ground.
How did it go?