Question

If (p+q)=3 then what is the value of (p3 + q3 ), when it is given that p=1/q?

a. 123

b. 143

c. 111

d. 132

Answer 1

p+q=3
and p=1/q
on putting value of p
p+1/p=3
(p^2+1)/p=3
p^2+1=3p
p^2-3p+1=0
and we know
p={-b+/-√(b^2-4ac)}/2
here b=-3,a=1,c=1
then
{3+/-√(9-4)}/2
[3+√5]/2=p and also p=[3+√5]/2