Application of Derivatives: 1 mark Questions (CBSE Class 12)
9 different 1 mark questions on Application of Derivatives from CBSE Class 12 Maths board exams 2026, newest first.
The least value of f(x)=x3−12x,x∈[0,3] is
- (A)−16
- (B)−9
- (C)0
- (D)16
Show answer & solution
Answer: (A) −16
- f′(x)=3x2−12=0⇒x=2 (in [0,3]).
- f(0)=0, f(2)=8−24=−16, f(3)=27−36=−9.
- Least value =−16.
The absolute maximum value of f(x)=x2+1 in [−5,2] is
- (A)26
- (B)1
- (C)5
- (D)2
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Answer: (A) 26
- f′(x)=2x=0⇒x=0.
- f(−5)=26, f(0)=1, f(2)=5.
- Absolute maximum =26.
The least value of f(x)=e−x in [0, 3] is
- (A)e−3
- (B)−1
- (C)1
- (D)−e3
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Answer: (A) e−3
- f′(x)=−e−x<0, so f is decreasing on [0, 3].
- Least value =f(3)=e−3.
For f(x)=x+x1 (x=0)
- (A)local maximum value is 2
- (B)local minimum value is −2
- (C)local maximum value is −2
- (D)local minimum value < local maximum value
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Answer: (C) local maximum value is −2
- f′(x)=1−x21=0⇒x=±1; f′′(x)=x32.
- f′′(−1)=−2<0: local maximum at x=−1, value f(−1)=−2.
- f′′(1)=2>0: local minimum at x=1, value f(1)=2.
- So the local maximum value is −2 (and it is less than the local minimum value 2).
The rate of change of volume of a sphere with respect to its diameter, when its radius is 5 cm, is :
- (A)400π cm3/cm
- (B)100π cm3/cm
- (C)50π cm3/cm
- (D)25π cm3/cm
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Answer: (C) 50π cm3/cm
- With diameter D, V=34π(2D)3=6πD3.
- dDdV=2πD2.
- At r=5, D=10: dDdV=2100π=50π cm3/cm.
The surface area of a sphere when its volume changes at the same rate as its radius is :
- (A)4π sq. units
- (B)1 sq. unit
- (C)4 sq. units
- (D)π sq. units
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Answer: (B) 1 sq. unit
- V=34πr3⇒dtdV=4πr2dtdr.
- Given dtdV=dtdr, so 4πr2=1.
- Surface area =4πr2=1 sq. unit.
If the distance travelled by a particle in t seconds is given by S=72t+3t2−t3, then time taken by the particle to come to rest is :
- (A)4 seconds
- (B)6 seconds
- (C)3 seconds
- (D)0 seconds
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Answer: (B) 6 seconds
- Velocity v=dtdS=72+6t−3t2.
- At rest v=0: t2−2t−24=0⇒(t−6)(t+4)=0.
- t>0, so t=6 seconds.
A cylindrical tank is being filled with sand at a rate of 314 m3/h. If the radius of the tank is 10 m, then the height of sand in the tank increases at the rate of :
- (A)1.1 m/h
- (B)1 m/h
- (C)π m/h
- (D)2π m/h
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Answer: (B) 1 m/h
- V=πr2h with r=10 fixed, so dtdV=100πdtdh.
- 314=100πdtdh⇒dtdh=π3.14.
- Taking π=3.14, dtdh=1 m/h.
Absolute minimum value of f(x)=(x−2)2+5 in the interval [−3,2] is :
- (A)−3
- (B)2
- (C)5
- (D)30
Show answer & solution
Answer: (C) 5
- f′(x)=2(x−2)≤0 on [−3,2], so f is decreasing there.
- Minimum is at x=2: f(2)=5 (maximum f(−3)=30).
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