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Unformatted text preview: t make any
mistakes in the factoring process.
[Return to Problems] (b) y 2 + 7 y
Here’s the number we’ll need this time.
2 49
æ7ö
ç ÷=
4
è2ø
It’s a fraction and that will happen fairly often with these so don’t get excited about it. Also,
leave it as a fraction. Don’t convert to a decimal. Now complete the square. 49 æ
7ö
y + 7y +
=çy+ ÷
4è
2ø 2 2 This one is not so easy to factor. However, if you again recall that this will ALWAYS factor as y
plus the blue number above we don’t have to worry about the factoring process.
[Return to Problems] It’s now time to see how we use completing the square to solve a quadratic equation. The process
is best seen as we work an example so let’s do that. Example 2 Use completing the square to solve each of the following quadratic equations.
(a) x 2  6 x + 1 = 0 [Solution]
(b) 2 x 2 + 6 x + 7 = 0 [Solution]
(c) 3 x 2  2 x  1 = 0 [Solution]
Solution
We will do the first problem in detail explicitly giving each step. In the...
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 Spring '12
 MrVinh

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