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If the points P(a + 2b + c), Q(2a + 3b), R (b + tc) are collinear, where a, b and c are three non-coplanar vectors, the value of t is |
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Answer» `-2` P(a + 2b + c), Q (2a + 3b) and R(B + t c) are collinear. `therefore PQ = lambda QR" for some SCALAR "lambda` `implies a+b-c=lambda(-2a-2b+tc)` `implies (2lambda+1)a+(1+2lambda)b-(t lambda+1)c=0` `implies 2lambda+1=0, 2lambda+1=0, tlambda+1=0` [`because` a, b and c are non-coplanar] implies t = 2 |
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