Solve the following inequalities
and write the solution set
using internal notation
i) x²- X>20
Answers
Question:
Solve the given inequality and write the solution set using interval notation.
• x² - x > 20
Answer:
x € (-∞,-4)U(5,∞)
Solution:
We have;
=> x^2 - x > 20
=> x^2 - x - 20 > 0
=> x^2 - 5x + 4x - 20 > 0
=> x(x - 5) + 4(x - 5) > 0
=> (x-5)(x+4) > 0
Two cases arises from the above inequation.
Case1 : (x-5) > 0 and (x+4) > 0
Case2 : (x-5) < 0 and (x+4) < 0
Case1 :
=> (x-5) > 0 and (x+4) > 0
=> x > 5 and x > - 4
=> x > 5
=> x € (5,∞)
Case2 :
=> (x-5) < 0 and (x+4) < 0
=> x < 5 and x < - 4
=> x < - 4
=> x € (-∞,-4)
Here,
The solution set of the given inequation will be given by the union set of case1 and case2.
Thus,
x € (-∞,-4)U(5,∞)
Hence,
Solution set :
x € (-∞,-4)U(5,∞)
Step-by-step explanation:
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