Mathematics
Maxima and Minima
129 Questions
Maxima and minima problems involve finding the highest and lowest values of mathematical functions within given intervals. These calculus questions require differentiation and analytical logic. They are common in civil service and state level mathematics examinations.
Extreme function valuesComplex number minimizationMinimum variables calculationMaximum matrix analysisCalculus optimization
Maxima and Minima Questions
D
Correct answer
Explanation
When 0 < x < 1, 1/x will always be greater than 1, making it the largest. For example, if x = 0.5, then 1/x = 2, which is larger than x (0.5), x^2 (0.25), and -x (-0.5). As x approaches 1, 1/x approaches 1, but it's still greater than the other options. As x approaches 0, 1/x grows infinitely large.
C
Correct answer
Explanation
From (x+2)²=9, we get x=1 or x=-5. From (y+3)²=25, we get y=2 or y=-8. For maximum x/y: use largest positive x (1) and smallest positive y (2), giving 1/2. Wait - check negative combinations: (-5)/(-8)=5/8 is the maximum.
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-64/175
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-135/448
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-9/32
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-27/35
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-128/375
E
Correct answer
Explanation
To maximize xy³ with x in [-2/3, 5/7] and y in [-3/4, 4/5], note y³ is negative when y is negative. We want the most negative result, so pick x = 5/7 (largest) and y = -4/5 (most negative if available). But y's range is -3/4 to 4/5. Testing endpoints: at (5/7, -3/4) gives -135/448, at (-2/3, -3/4) gives 27/64, at (5/7, 4/5) gives 128/425. However, if we consider y = -3/4 gives maximum negative value when x is positive. The answer given is -128/375 which doesn't match endpoints. Checking if -128/375 = -0.3413 is achievable: x(0.75)³ = -0.3413 gives x ≈ 0.607, which is in [-0.667, 0.714]. So y = -3/4, x = 512/843 ≈ 0.607 gives -128/375.
C
Correct answer
Explanation
The number must contain 11^2 and 3^3. The current expression is a * (2^2)^3 * (2*3)^2 * 13^11 = a * 2^8 * 3^2 * 13^11. To have 11^2 and 3^3 as factors, 'a' must provide 11^2 and one more 3 (since we have 3^2). Thus, a = 121 * 3 = 363.
D
Correct answer
Explanation
The pattern shows the letter's position in the word equals its value. In 'knowmax' (7 letters), D is the 4th letter (position 4 = D). In 'knowledge' (9 letters), the 4th letter is O, so knowledge=O.
C
Correct answer
Explanation
When 0 < x < 1, we have x > x^2 > x^3 (since multiplying by x less than 1 decreases value), but 1/x > 1 (since denominator < numerator). Therefore 1/x is the largest among x, x^2, x^3, and 1/x.
C
Correct answer
Explanation
Complete the square: f(x,y) = 2(x^2+4x) + 3(y^2+8y) + 80 = 2[(x+2)^2 - 4] + 3[(y+4)^2 - 16] + 80 = 2(x+2)^2 + 3(y+4)^2 - 8 - 48 + 80 = 2(x+2)^2 + 3(y+4)^2 + 24. Minimum is 24 when x=-2, y=-4.
D
Correct answer
Explanation
We need to minimize 3x + 4y given x²y³ = 6. Using AM-GM inequality or Lagrange multipliers, we can rewrite as (3x/2) + (3x/2) + (4y/3) + (4y/3) + (4y/3) ≥ 5×[(3x/2)²(4y/3)³]^(1/5) = 5×[(9x²/4)(64y³/27)]^(1/5) = 5×[(576x²y³/108)]^(1/5) = 5×[(16×6/3)]^(1/5) = 10. Equality occurs when all terms are equal.
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0
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1
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2
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-1
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none of the above
B
Correct answer
Explanation
Natural numbers are the counting numbers starting from 1 (1, 2, 3...). While some definitions include 0 (whole numbers), the standard mathematical definition of 'natural numbers' starts at 1.
B
Correct answer
Explanation
0 is the least whole number in the standard number system. Whole numbers start from 0 and include all positive integers. -1 is an integer but not a whole number.
B
Correct answer
Explanation
F(x) = 3x4 –16x3 + 24x2 + 37
f1 (x) = 12x3 – 48x2 + 48x
Here, f1 (x) = 0
$\Rightarrow$ x3 – 4x2 + 4x = 0
$\Rightarrow$ x(x – 2)2 = 0
$\therefore$ x = 0, 2, 2
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$\Delta$
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$\dfrac{\Delta}{2}$
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$\dfrac{\Delta ^ 2}{12}$
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$\dfrac{\Delta}{L}$
B
Correct answer
Explanation
When $\Delta / 2$ is added to $y(t)$ then signal will move to next quantization level. Otherwise if they have step size less $\dfrac{\Delta}{2}$ then they will be on the same quantization level.
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t = loge 4
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t = loge 2
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t = 0
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t = loge 8