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I need help using Quadratic Functions and completing the square.(Algebra 2)?
The problem is x(squared)-8x=12.
I know how to set up the operation: x(squared)-8x__=12+__
Now I substitute the blanks with (b/2a): x(squared)-8x+16=12+16
Then I factor: (x-4)(squared)=28
Next I find the square roots: x-4= the square root of 28
Add and simplify:x=4+or-2*the square root of 7
I hope this is understandable, but I don't understand how to simplify the square root of 28 to 2 times the square root of 7. I would be most greatful if somebody helped me out and explained how to me.
1 Answer
- Kyle SLv 68 years agoFavorite Answer
Whenever you are simplifying radicals, you are looking for perfect squares.
If you can't automatically see a perfect square, you can also write out a number as its prime factors and look for pairs.
√28 = √(2 * 2 * 7) = √(2 * 2) * √7 = √4 * √7 = 2 √7
Source(s): Math teacher