If p + m = 6 and p^{3}+m^{3}=72,then the value of pm is

SSC CGL Tier II 12 Apr 2015 Paper

Question : 24 of 100

Marks: +1, -0

p + m = 6

and

p^{3}+m^{3}=72,

then the value of pm is

Solution:

(4)

(p+m)^{3}=p^{3}+m^{3}+3 p m(p +m )

⇒(6)^{3}=72+3 p m ×6

⇒ 216-72=18 p m

⇒ 18 p m=144

⇒ p m=144 ÷18=8

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