3,4 < √ 12 < 3,6 <br>( 3,4 )^2 < ( √ 12 )^2 < ( 3,6 )^2
11,56 < 12 < 12,96
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√ X = 4
( √ X )^2 = 4 ^2
X > 0
X = 16
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2X^2 - 5X - 3 = 0
D = 25 + 24 = 49 ; √ D = 7
X1 = ( 5 + 7 ) : 4 = 3
X2 = ( 5 - 7) : 4 = 0,5
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X^2 - 5X + 6 = 0
X1 + X2 = 5
X1 * X2 = 6
x1 = 3
X2 = 2