CBSE Class 12 Math 2022 Term I Solved Paper

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Question : 17
Total: 50
The equation of the tangent to the curve y(1+x2) =2−x, where it crosses the X-axis is
We have, equation of the curve y(1+x2)=2−x...(i)
∴y⋅(0+2x)+(1+x2)⋅‌
dy
dx
=0−1‌ [on differentiating w.r.t.x] ‌

⇒2‌xy+(1+x2)‌
dy
dx
=−1

⇒‌
dy
dx
=‌
−1−2‌xy
1+x2
.
.
.
‌ (ii)
‌

Since, the given curve passes through x− axis i.e., y=0.
∴O(1+x2)=2−x‌ [using Eq.(i)] ‌
⇒x=2
So, the curve passes through the point (2,0).
∴(‌
dy
dx
)
(2,0)
=‌
−1−2×0
1+22
=−‌
1
5
=‌ slope of the curve ‌

∴ slope of tangent to the curve =−‌
1
5

∴ Equation of tangent of the curve passing through (2,0) is
y−0=−‌
1
5
(x−2)

⇒5y=−x+2
⇒5y+x=2
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