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Solution - Career Point

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12.[A, B, C, D]13.[B]2x t − 5t + 4Let F(x) =∫dt0t2 + e⇒ F′(x) =2So from F′(x) = 0, we get x = 0 orHence x = 0, ±2, ±1.x = –4Shaded region is S 0 . Area of S 0= 4 × 2 – 21 π (1) 2 = 8 – π/214.[D] y ∈ [0, 4], x ∈ [–1, 1]m (t) = costlines y = 2x + 0.4 lies inside the region so⇒ t ∈ [0, 1]t 2 + (2t + 0.4) 2 – 1 ≥ 0 ⇒ t ∈ [0.28, 1]15.[B] (Slope) max. = (cos t) max = cos (0.28) and point is(π, 1)16.[C]18.[A]24 2x − 5x + 4.2xx2 + ex 2 5 ± 25 −165 ± 3== = 4, 12 2DCy = +4–1 1x = 4Ay = –4 B1 r1=2 r23= 13( −1)−1(3)− 6= = – 33 −12x + RTy −1= cos (0.28)x − πC SC Sx =17.[D] tangents = y = ±3tan30º = 32•C 2C 160º1(h + 1) 2 + k 2 = (1 + 2) 2 (circle)Column Matching19. [A] → r; [B] → p,r; [C] → s; [D] → r10(A) ∑ 20 C r = 20 C 0 + 20 C 1 +……+ 20 C 10r=0But, 20 C 0 + 20 C 1 +……+ 20 C 20 = 2 20(B) ∑r=Also, 20 C 20 = 1 = 20 C 0 , 20 C 19 = 20 C 1 , 20 C 18 = 20 C 2etc.∴ given sum = ( 20 C 0 + 20 C 1 +……+ 20 C 20 )– ( 20 C 11 +…..+ 20 C 20 )2 20 + 20 C 10 – ( 20 C 10 + 20 C 9 + ……+ 20 C 0 )∴ 2 ( 20 C 0 + 20 C 1 +…..+ 20 C 10 )= 2 20 + 20 C 101000100 C r (x –3) 100–r 2 r= ((x–3) +2) 100 = (x –1) 100 = (1 –x) 100100100∑r=0C r ( −x)= ∑=r100r0r( −1)( −1)r 100C x∴ Coeff. of x 53 = (–1) 53 100 C 53 = – 100 C 53(C) We have(1+ x) 10 = 10 C 0 + 10 C 1 x + 10 C 2 x 2 +……+ 10 C 10 x 10....(1)Also (1–x) 10 = 10 C 0 – 10 C 1 x + 10 C 2 x 2 +…….…..+ 10 C 10 x 10 ....(2)Multiplying, we get(1 –x 2 ) 10 = ( 10 C 0 + 10 C 1 x + 10 C 2 x 2 +……….+10 C 10 x 10 ) × ( 10 C 0 – 10 C 1 x +10 C 2 x 2 +……...+ 10 C 10 x 10)Equating the coefficients of x 10 , we get10 C 5 (–1) 5 = 10 C 10 0 C 10 – 10 C 10 1 C 9 + 10 C 10 2 C 8 +…….+ 10 C 10 10 C 0⇒ – 10 C 5 = ( 10 C 0 ) 2 – ( 10 C 1 ) 2 + ( 10 C 2 ) 2 +………+ ( 10 C 10 ) 2rrXtraEdge for IIT-JEE 91APRIL 2010

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