2x^2-7x+3<0 X^2-2x>0
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13 января 2025 14:54
To solve the inequalities (2x^2 - 7x + 3 < 0) and (x^2 - 2x > 0), we'll handle each one separately.
Step 1: Solve (2x^2 - 7x + 3 < 0)
First, find the roots of the equation (2x^2 - 7x + 3 = 0) using the quadratic formula:
[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} ]
Here, (a = 2), (b = -7), and (c = 3).
Calculating the discriminant:
[ b^2 - 4ac = (-7)^2 - 4(2)(3) = 49 - 24 = 25 ]
Now substituting in the quadratic formula:
[ x = \frac{7 \pm \sqrt{25}}{2(2)} = \frac{7 \pm 5}{4} ]
This gives us two solutions:
- (x = \frac{12}{4} = 3)
- (x = \frac{2}{4} = \frac{1}{2})
Now we have roots (x = \frac{1}{2}) and (x = 3).
Testing intervals for (2x^2 - 7x + 3 < 0)
The intervals to test are:
- ( (-\infty, \frac{1}{2}) )
- ( \left(\frac{1}{2}, 3\right) )
- ( (3, \infty) )
Test (x = 0) in ((- \infty, \frac{1}{2})): [ 2(0)^2 - 7(0) + 3 = 3 > 0 \quad \text{(not in solution)} ]
Test (x = 1) in (\left(\frac{1}{2}, 3\right)): [ 2(1)^2 - 7(1) + 3 = 2 - 7 + 3 = -2 < 0 \quad \text{(in solution)} ]
Test (x = 4) in ((3, \infty)): [ 2(4)^2 - 7(4) + 3 = 32 - 28 + 3 = 7 > 0 \quad \text{(not in solution)} ]
Thus, the solution for (2x^2 - 7x + 3 < 0) is: [ \left(\frac{1}{2}, 3\right) ]
Step 2: Solve (x^2 - 2x > 0)
Factoring the expression gives us: [ x(x - 2) > 0 ]
Finding the roots:
- (x = 0)
- (x = 2)
Testing intervals for (x^2 - 2x > 0)
The intervals to test are:
- ( (-\infty, 0) )
- ( (0, 2) )
- ( (2, \infty) )
Test (x = -1) in ((- \infty, 0)): [ (-1)(-1 - 2) = (-1)(-3) = 3 > 0 \quad \text{(in solution)} ]
Test (x = 1) in ((0, 2)): [ (1)(1 - 2) = (1)(-1) = -1 < 0 \quad \text{(not in solution)} ]
Test (x = 3) in ((2, \infty)): [ (3)(3 - 2) = (3)(1) = 3 > 0 \quad \text{(in solution)} ]
Thus, the solution for (x^2 - 2x > 0) is: [ (-\infty, 0) \cup (2, \infty) ]
Step 3: Combine the solutions
We now need to find the intersection of the solutions:
- From the first inequality: (\left(\frac{1}{2}, 3\right))
- From the second inequality: ( (-\infty, 0) \cup (2, \infty) )
The intersection is found within the interval (\left(\frac{1}{2}, 3\right)):
- The only overlapping portion is ( (2, 3) ).
Final Solution
The final solution to the system of inequalities is: [ (2, 3) ]
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