Question

If the given points be A(a, 2, 1) and (1, −1, 1) is 5, then find the value(s) of a

Answer 1

Let the given points be A(a, 2,1) and B(1, −1,1)

∴ AB = 5

\({\sqrt{{(a-1)}^{2}+(2+1)^{2}+(1-1)^{2}}}\)

⇒ a² − 2a + 1 + 9 = 25 

⇒ a² − 2a − 15 = 0 

⇒ a² − 5a + 3a − 15 = 0

⇒ (a − 5)(a+ 3) = 0 

∴ a = 5, −3