Question
Download Solution PDFIf x ∈ R, then minimum and maximum limit of
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe correct option is ( 3 ).
Concept :
Maximum and Minimum Values of the Quadratic Expression :
Let's suppose y = ax2 + bx + c ,
when determining the maximum and minimum values of ax2 + bx + c.
suppose x is real ,then the descriminant of equation
ax2 + bx + c - y = 0
⇒ b2 - 4a(c - y) = 0
Calculation :
Let,
y =
yx2 + 2xy + 9y = x2 - 2x + 9
x2 ( y - 1 ) + x ( 2y + 2 ) + 9 ( y - 1 ) = 0
Now,
D = 0
b2 - 4ac = 0
⇒ ( 2y + 2 )2 - 4( y - 1 )
4y2 + 4 + 8y - 36y2 - 36 + 72y = 0
32y2 - 80y + 32 = 0
2y2 - 5y + 2 = 0
2y ( y - 2 ) - 1 ( y - 2 ) = 0
( y - 2 ) ( 2y - 1 ) = 0
⇒ y = 2 and ,
Thus,
maximum value of the function = 2
minimum value of the function =
Hence, The correct option is ( 3 ).
Last updated on Jul 19, 2025
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