MHT CET202311 May 2023Evening ShiftMathematicsComplex NumberActual
If x= 5 1-2 i , i = -1 , then the value of x^3+x^2-x+22 is
Options
- A7
- B9
- C17
- D39
Correct answer
A. 7
Step-by-step solution
aligned & x= 5 1-2 i = 5(1+2 i ) 1+4 =1+2 i & x^2=(1+2 i )^2=1-4+4 i =-3+4 i & x^3=(-3+4 i )(1+2 i ) & =-3-6 i+4 i-8 & =-11-2 i & x^3+x^2-x+22 & =(-11-2 i )+(-3+4 i )-(1+2 i )+22 & =-11-2 i -3+4 i -1-2 i +22 & =7 & aligned