Question 85

Find the value of p if -3x - 11, x + p and 5x + 7 are in arithmetic progression.

Solution

Terms in arithmetic progression : $$(-3x - 11) , (x + p) , (5x + 7)$$

=> Difference between first two terms is equal to the difference between last two terms

=> $$(x + p) - (-3x - 11) = (5x + 7) - (x + p)$$

=> $$4x + p + 11 = 4x + 7 - p$$

=> $$2p = 7 - 11 = -4$$

=> $$p = \frac{-4}{2} = -2$$

=> Ans - (D)

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