Activity
Solve each equation. Use the notation when appropriate and express radicals in simplest form.
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Enter the solution to the equation.
Enter the solution to the equation.
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No real solution
So far in this activity you encountered radical solutions that were easy to simplify. Sometimes you will get radical solutions like . Let’s review how to simplify more difficult radicals using perfect squares.
Step 1 - Look at the ways to factor the number under the radical.
For example, factor 12 from .
and
Step 2 - Choose the factorization of the number that includes a perfect square. Rewrite the number under the radical using that factorization.
Step 3 - Recall that .
Step 4 - Simplify the perfect squares.
So
Compare your answer:
Compare your answer:
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(or equivalent)
Video: Solving Quadratics with Square Roots
Watch the following video to learn more about equations with solutions that are square roots.
Self Check
Additional Resources
Solving Quadratics with Radical Solutions
When solving quadratic equations, it is important to remember that:
- Any positive number has two square roots, one positive and one negative, because there are two numbers that can be squared to make that number. (For example, and both equal 36, so 6 and -6 are both square roots of 36.)
- The square root symbol can be used to express the positive square root of a number. For example, the square root of 36 is 6, but it can also be written as because .
- To express the negative square root of a number, say 36, we can write -6 or .
- When a number is not a perfect square (for example, 40), we can express its square roots by writing and .
How could we write the solutions to an equation like ? This equation is saying, “something squared is 11.” To make the equation true, that something must be or .
We can write:
or
or
A more compact way to write the two solutions to the equation is: .
Try it
Try It: Solving Quadratics with Radical Solutions
Solve .
Here is how to solve this quadratic equation:
Step 1 - Make sure the quadratic is isolated on one side.
Step 2 - Take the square root of both sides.
Step 3 - Simplify.
Step 4 - Solve the equation. For this problem, add 2 to each side.
Step 5 - Simplify.
,