Summer Clouds moderators
07/07/2017 at 08:45-
x2 + 4x + 5
= x2 + 2.2.x + 22 + 1
= (x + 2)2 + 1
We have : \(\left(x+2\right)^2\ge0\)
=> \(\left(x+2\right)^2+1\ge1\)
=> Min = 1
<=> (x + 2)2 = 0
<=> x + 2 = 0
<=> x = -2
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