find the value of n (n+3) x^2-(5-n) x+1=0 has coincident roots
Answers
Question :
Find the value of n for which the quadratic equation (n+3)x² - (5-n)x + 1 = 0 has coincident roots .
Answer :
n = 1 , 13
Note:
★ The possible values of the variable which satisfy the equation are called its roots or solutions .
★ A quadratic equation can have atmost two roots .
★ The general form of a quadratic equation is given as ; ax² + bx + c = 0 .
★ The discriminant , D of the quadratic equation ax² + bx + c = 0 is given by ;
D = b² - 4ac
★ If D = 0 , then the roots are real and equal .
★ If D > 0 , then the roots are real and distinct .
★ If D < 0 , then the roots are unreal (imaginary) .
Solution :
Here ,
The given quadratic equation is ;
(n+3)x² - (5-n)x + 1 = 0
Now ,
Comparing the given quadratic equation with the general quadratic equation ax² + bx + c = 0 , we have b;
a = n + 3
b = -(5-n) = n - 5
c = 1
For equal or coincident roots , the discriminant of the given quadratic equation must be zero .
Thus ,
=> D = 0
=> b² - 4ac = 0
=> (n - 5)² - 4•(n + 3)•1 = 0
=> n² - 10n + 25 - 4n - 12 = 0
=> n² - 14n + 13 = 0
=> n² - n - 13n + 13 = 0
=> n(n - 1) - 13(n - 1) = 0
=> (n - 1)(n - 13) = 0
=> n = 1 , 13
Hence , n = 1 or 13 .
Answer:
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