Question 168650
10p^2c^2 + 7pcr = 12r^2

12r^2 - 7pcr - 10p^2c^2 = 0

Use the quadratic formula:

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r = [7pc +- sqrt(49p^2c^2 - 4*12*-10p^2c^2)]/24

r = [7pc +- sqrt(529p^2c^2)]/24

r = [7pc +- 23pc]/24

r = [30pc]/24 or r = [-16pc]/24

r = [15/12]pc or [-2/3]pc

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Cheers,
Stan H.