We'll impose the constraint of existence of square
roots:
x^2 - 5x + 4>=0
We'll
re-write the
inequality:
(x-1)(x-4)>=0
The
intervals of admissible values are (-infinte ,1)U(4 ,
+infinite).
x^2 + 3x -2>=0
x1 =
[-3+sqrt(9+8)]/2
x1 = (-3+sqrt17)/2
x2
= (-3+sqrt17)/2
The intervals of admissible values are (-infinte
,(-3+sqrt17)/2)U((-3+sqrt17)/2 , +infinite).
The solution of the
equation has to belong to the intervals of admissible
values:
(-infinte ,(-3+sqrt17)/2)U(4 ,
+infinite).
Now, we can solve the equation by raising to square both
sides, to get rid of the square roots:
( x^2 - 5x + 4 ) = ( x^2 + 3x
-2)
We'll eliminate and combine like
terms:
-5x - 3x + 4 + 2 = 0
-8x + 6 =
0
-8x = -6
x =
6/8
x = 3/4
We notice
that the value for x doesn't belong to the interval of admissible values for x, so the equation
has no solution.
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