Question

If x = 2+√5 then the value of(x3-3 is:​

Answer 1

Answer:

Step-by-step explanation:

As we see that the x has a power of 3 so we begin by cubbing the whole equation.

So we start solving like:

x+1x=3  

(x+1x)3=33  

x3+3.x2.1x+3.x.1x2+1x3=27  

(x3+1x3)+3.x2.1x+3.x.1x2=27  

x3+1x3+(3x+3x)=27  

x3+1x3+3(x+1x)=27  

x3+1x3+3×3=27  

x3+1x3+9=27  

x3+1x3=18  

Therefore the answer is 18