AP EAMCET201921 Apr 2019Morning ShiftMathematicsVector AlgebraActual

Let A=( , 1,2 ), B=(3,1,2) and C =4 i - j +3 k . If A B C =6 i +9 j -5 k , then ^2+ +5=

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Correct answer

B. 7

Step-by-step solution

Given, aligned & A=( , 1,2 ) & B=(3,1,2) & C =4 i - j +3 k aligned and Now, A B =(3- ) i +(2-2 ) k aligned & A B C = | array ccc i & j & k 3- & 0 & 2-2 4 & -1 & 3 array | & = i (2-2 )- j (9-3 -8+8 )+ k (-3+ ) & =(2-2 ) i +(5 -1) j +( -3) k aligned Comparing it with 6 i +9 j -5 k , then aligned & 2-2 =6,5 -1=9 and -3=-5 & 2 =-4 & =-2 & ^2+ +5=(-2)^2-2+5 & =4-2+5=7 & aligned

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