solve by completing the square x^2-10x+21=0?

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solve by completing the square x^2-10x+21=0?

2007-12-23 06:39:54 · 2 answers · asked by blue_eyed_woman_23 3 in Science & Mathematics ➔ Mathematics

2 answers

x² - 10x = -21

Add 25 to both sides (10 / 2)²

x² - 10x + 25 = -21 + 25
(x - 5)² = 4

Take the square root of both sides:

x - 5 = ± 2

x - 5 = 2
x = 7

or

x - 5 = -2
x = 3

x = 7 or x = 3

2007-12-23 06:43:35 · answer #1 · answered by Jacob A 5 · 0⤊ 0⤋

x Â² - 10 x + 25 = 25 - 21
( x - 5 ) Â² = 4
( x - 5 ) = Â± 2
x = 7 , x = 3

2007-12-23 15:06:26 · answer #2 · answered by Como 7 · 1⤊ 0⤋