SOLUTION: Please help me solve this problem: Solve problem and write in interval notation if problem does not have a solution state why?
2x2 − 4x − 1 > 0
Thank you!
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-> SOLUTION: Please help me solve this problem: Solve problem and write in interval notation if problem does not have a solution state why?
2x2 − 4x − 1 > 0
Thank you!
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Question 994042: Please help me solve this problem: Solve problem and write in interval notation if problem does not have a solution state why?
2x2 − 4x − 1 > 0
Thank you! Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! 2x2 − 4x − 1 > 0
Set it equal to zero and look at roots
2x^2-4x-1=0
quadratic formula
x=(1/4) {4+/- sqrt (16+8)}
x=(1/4) {4 +/-sqrt 24}
sqrt 24=4.9
x=(1/4)(4+/- 4.9}
roots are 2.225 and -0.225. Those are critical values.
Look at -1, to the left of the smallest root.
2+4-1 is > 0, so that works.
Look between the roots, zero is a good choice.
-1 is not >0, so that doesn't work.
Use 3, and 18-12-1 > 0, and that works.
(-oo,-0.225] and [2.225,oo)
Graphing is always useful here. Look at the graph above y=0.
