Question

The distance between point (3,0) and (7, 2p) is √80. Find the value of p.
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Answer 1

Distance = √[ ( 7 - 3 )^2 + ( 2p - 0 )^2 ]

Distance = √(4)^2 + ( 2p)^2

Distance = √16 + 4p^2

As the question said : Distance = √80

√80 = √16 + 4p^2

Thus :

16 + 4p^2 = 80

Subtract both sides 16

16 - 16 + 4p^2 = 80 - 16

4p^2 = 64

Divide both sides by 4

4p^2 ÷ 4 = 64 ÷ 4

p^2 = 16

Thus :

p = 4 or p = - 4