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CBSE Class 12 Math 2020 Outside Delhi Set 1 Solved Paper

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Question : 14 of 36
Marks: +1, -0
The slope of the tangent to the curve y=x3−x at the point (2,6) is____________
OR
The rate of change of the area of a circle with respect to its radius r, when r=3‌cm, is________
Solution:     👈: Video Solution
y=x3−x
‌
dy
dx
=3x2−1
‌ slope of tangent ‌=‌
dy
dx

=3x2−1
x=2
‌ Slope of tangent ‌‌=3(2)2−1
‌=12−1
‌=11


OR
6πcm2∕cm
Explanation: Area of circle, A=πr2
∴‌‌‌
dA
dr
‌=2πr
[‌
dA
dr
]r=3‌cm‌=2×π×3
‌=6πcm2∕cm
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