Simplifying Radicals
Radicals
Simplifying Radicals Express 45 as a product using a square number Separate the product Take the square root of the perfect square
Some Common Examples
Harder Example Find a perfect square number that divides evenly into 245 by testing 4, 9, 16, 25, 49 (this works)
Addition and Subtraction You can only add or subtract “like” radicals You cannot add or subtract with
More Adding and Subtracting You must simplify all radicals before you can add or subtract
Multiplication Consider each radical as having two parts. The whole number out the front and the number under the radical sign. You multiply the outside numbers together and you multiply the numbers under the radical signs together
More Examples Note that can be simplified
Try These
Division As with multiplication, we consider the two parts of the surd separately.
Division
Important Points to Note Radicals can be separated when you have multiplication and division However Radicals cannot be separated when you have addition and subtraction
Rational Denominators Radicals are irrational. A fraction with a radical in the denominator should to be changed so that the denominator is rational. Here we are multiplying by 1 The denominator is now rational
More Rationalising Denominators Multiply by 1 in the form Simplify
Review Difference of Squares When a radical is squared, it is no longer a radical. It becomes rational. We use this and the process above to rationalise the denominators in the following examples.
More Examples Here we multiply by 5 – which is called the conjugate of 5 + Simplify
Another Example Here we multiply by the conjugate of which is Simplify
Try this one The conjugate of is Simplify See next slide
Continuing
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