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JEE Mains · Maths · STD 12 - 6. Application of derivatives

If the tangent to the curve \(y=x^{3}-x^{2}+x\) at the point \((a, b)\) is also tangent to the curve \(y=5 x^{2}+\) \(2 x -25\) at the point \((2,-1)\), then \(|2 a +9 b |\) is equal to \(........\)

  1. A \(196\)
  2. B \(194\)
  3. C \(195\)
  4. D \(193\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(195\)

Step-by-step Solution

Detailed explanation

\(y=5 x^{2}+2 x-25 \quad P(2,-1)\) \(y^{\prime}=10 x+2\) \(y_{P}^{\prime}=22\) \(\therefore\) tangent to curve at \(P\) \(y+1=22(x-2)\) \(y=22 x-45\) \(y=x^{3}-x^{2}+x\) \(\left.\frac{ dy }{ dx }\right|_{ C _{2}}=3 x ^{2}-2 x +1\)…