Question

f t + 1/t = 8 then find the value of [ t + 1/t ] ^3

Answer 1

Step-by-step explanation:

If t+1/t=8, then

t3+3t+3/t+1/t3=83

t3+1/t3=83-3(t+1/t)=83-3*8=8(82-3)=8*61=488.

t3+1/t3=488

Now denote u=t3. Then

u+1/u=488

u2-488u+1=0

You can solve for u and then find t but it gets a little complicated.

But if you want to find t from

t+1/t=8, then you multiply by t and get

t2-8t+1=0.

The answer is

t1=4-√15, t2=4+√15.