Question 1087723: Solve the quadratic inequality. Write the solution set in interval notation. Show the complete solution.
𝑥(𝑥+1)>112−5𝑥
Answer by ikleyn(52780) (Show Source):
You can put this solution on YOUR website! .
x*(x+1) > 112 -5x, ====> (equivalent transformation) ====>
x^2 + x > 112 - 5x, ====> (equivalent transformation) ====>
x^2 +x + 5x - 112 > 0, ====> (equivalent transformation) ====>
x^2 + 6x - 112 > 0.
Factor left side. You will get
(x+14)*(x-8) > 0, or, equivalently
(x-(-14)*(x-8) > 0. (1)
1) If x < -14 then each factor in the left side of (1) is negative,
so the product is positive.
2) If -14 < x < 8 then the factor (x-(-14)) is positive, while the factor (x-8) in the left side of (1) is negative,
so the product is negative.
3) If 8 < x then each factor in the left side of (1) is positive,
so the product is positive.
Answer. The given inequality has the union of segments ( , }}}] U [ , ) as the solution set.
Solved.
If you want to learn on how to solve quadratic inequalities, read the lesson
- Solving problems on quadratic inequalities
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lesson is the part of this online textbook under the topic "Inequalities".
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