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# how do you solve x^2 +12x +25=0 by completing the square?

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how do you solve x^2 +12x +25=0 by completing the square?

Guest Jun 4, 2015

#1
+26640
+10

Look at the first two terms.  Form (x + half the coefficient of the 2nd term)2

This is (x + 6)2 which can be expanded as x2 + 12x + 36

This, in turn can be written as x2 + 12x + 25 + 11, so if x2 + 12x + 25 = 0 then x2 + 12x + 36 = 11

Or  (x + 6)2 = 11

x+ 6 = ±√11

x = -6 ±√11

.

Alan  Jun 4, 2015
Sort:

#1
+26640
+10

Look at the first two terms.  Form (x + half the coefficient of the 2nd term)2

This is (x + 6)2 which can be expanded as x2 + 12x + 36

This, in turn can be written as x2 + 12x + 25 + 11, so if x2 + 12x + 25 = 0 then x2 + 12x + 36 = 11

Or  (x + 6)2 = 11

x+ 6 = ±√11

x = -6 ±√11

.

Alan  Jun 4, 2015

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