Question
f(x)=x2−3x+4x2+3x+4 the range of f(x) is
Answer: Option D
:
D
y=x2−3x+4x2+3x+4
yx2+3xy+4y=x2−3x+4
x2(y−1)+3x(y+1)+4(y−1)=0
D ≥0⇒9(y+1)2−4.4(y−1)2≥0
(3(y+1)−4(y−1)) (3(y+1)+4(y−1))≥0
(−y+7)(7y−1)≥0
(y−7)(y−17)≤0
17≤y≤7
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:
D
y=x2−3x+4x2+3x+4
yx2+3xy+4y=x2−3x+4
x2(y−1)+3x(y+1)+4(y−1)=0
D ≥0⇒9(y+1)2−4.4(y−1)2≥0
(3(y+1)−4(y−1)) (3(y+1)+4(y−1))≥0
(−y+7)(7y−1)≥0
(y−7)(y−17)≤0
17≤y≤7
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