In how many different ways can seven children line up in one row to have their picture taken?
2 answers:
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Answer:
x = - 1, x = 7
Step-by-step explanation:
Given
x² - 6x = 7
To complete the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(- 3) x + 9 = 7 + 9
(x - 3)² = 16 ( take the square root of both sides )
x - 3 = ± = ± 4
Add 3 to both sides
x = 3 ± 4, that is
x = 3 + 4 = 7 or x = 3 - 4 = - 1
