Question 1163105
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The last line  MUST  BE  COMPLETED  in this way


    
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4-9i^2 = 4 -9*(-1) = 4 + 9 = 13.     &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<U>the final ANSWER</U>



to eliminate any mentioning of the imaginary unit  &nbsp;" i "


(although &nbsp;" i^2 " is just a real number &nbsp;-1).