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Discussion Response Post to: r d sharma ,desperate and immediate help

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Titun (1467)

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total posts: 374
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The parametric equations for the parabola, y = x² are x = t and y = t²
Therefore, let the coordinates of A be (t₁, t_1²) and the coordinates of B be (t₂,t_2²)

Bold letters represent vectors.

Let, i and j be the unit vectors along OX and OY respectively.

Therefore,
OA = t₁i + t_1²j
OB = t₂ i + t_2²j

Now, OA . i = 1

t₁ = 1 ................... eqn. (1)
OB . i = - 2

t₂ = - 2 ................ eqn (2)

So, OA = i + j
OB = - 2 i + 4 j

Hence, 2OA - 3OB = 8 i - 10 j
So, l 2OA - 3OB l =

(8² + 10²) =

164 units.

Ans :

164 units

Cheers !!!

You never know what is enough till you know what is more than enough. Titun

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