The sum 35+213+35−213 equals (A)23(B)4365(C)21+613(D)32(E)none of these
Multiple choice: answer with the letter of the option you want.
Solution
Lets set our original expression equal to x. So 35+213+35−213=x. Cubing this gives us x3=(35+213+35−213)3=5+213+5−213+3(35+213∗35−213)(35+213+35−213)=10−9x So we have x3+9x−10=0. We can easily see that 1 is a root of this polynomial. By synthetic division, the new polynomial is x2+x+10, which has no real roots. Thus 35+213+35−213=1. Since 1 is not A-D, our answer is E.
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