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Question
Write f(x) = x2 + 5x + 4 in completed square form
Solution
The given quadratic equation is
f(x) = x2 + 5x + 4
Let y = x2 + 5x + 4
y – 4 = x2 + 5x
`y - 4 + 25/4 = x^2 + 2 xx 5/2 xx x + 25/4`
`y + (25 - 16)/4 = x^2 + 2 xx 5/2 xx x + (5/2)^2`
`y + 9/4 = (x + 5/2)^2`
y = `(x + 5/2)^2 - 9/4`
y = `(x + 5/2)^2 - (3/2)^2`
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