The coordinates of P, Q & R are (6,-11), (k,-9) & (2k,-3) respectively. If gradient of PQ=gradient of PR, find the value of k.

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P(6,-11) Q(k,-9) R(2k,-3)

gradient of PQ = gradient of PR

==> (-9--11)/(k-6) = (-3--11)/(2k-6)

==> 2/(k-6) = 8/(2k-6)

==> 2/(k-6) = 4/(k-3)

==> corss multiply:

==> 2(k-3) = 4(k-6)

==> (k-3) = 2(k-6)

==>  k-3 = 2k -12

==> k = 9

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