√x²+x-2
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21 января 2025 05:24
To solve the inequality ( \sqrt{x^2 + x - 2} < x ), we start by isolating the square root:
Square both sides (keeping in mind that squaring can introduce extraneous solutions, so we will verify later): [ x^2 + x - 2 < x^2 ]
Subtract ( x^2 ) from both sides: [ x - 2 < 0 ]
Rearranging gives: [ x < 2 ]
Next, we need to ensure our solution doesn't include extraneous solutions introduced by squaring. The original inequality has a square root, so we also need to ensure that the expression under the square root is non-negative:
Set the expression under the square root greater than or equal to zero: [ x^2 + x - 2 \geq 0 ]
Factor the quadratic: [ (x - 1)(x + 2) \geq 0 ]
Find the critical points: The roots of the equation are ( x = 1 ) and ( x = -2 ).
Test intervals around the critical points:
- For ( x < -2 ): Choose ( x = -3 ), then ( (-3 - 1)(-3 + 2) = (-4)(-1) = 4 \geq 0 ) (true).
- For ( -2 < x < 1 ): Choose ( x = 0 ), then ( (0 - 1)(0 + 2) = (-1)(2) = -2 < 0 ) (false).
- For ( x > 1 ): Choose ( x = 2 ), then ( (2 - 1)(2 + 2) = (1)(4) = 4 \geq 0 ) (true).
Determine the solution intervals from the checks:
- The inequality is satisfied in the intervals ( (-\infty, -2] ) and ( [1, \infty) ).
Combine the results: We need ( x < 2 ) from step 3 and ( (x \leq -2) \cup (x \geq 1) ) from step 8.
- The solutions ( x < 2 ) and ( x \geq 1 ) gives ( 1 \leq x < 2 ).
- The set ( (-\infty, -2] ) does not intersect with ( x < 2 ).
Final Consideration: Therefore, the solution to the inequality ( \sqrt{x^2 + x - 2} < x ) is: [ \boxed{[1, 2)} ]
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