Question 1106885
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1 + 2 = 3
4 + 5 + 6 = 7 + 8
9 + 10 + 11 +12 = 13 + 14 +15 <br>
Just to take the pattern one further:
16 + 17 + 18 + 19 + 20 = 21 + 22 + 23 + 24<br>
The last numbers for the 1st, 2nd, 3rd, and 4th equations are 3, 8, 15, 24.<br>
Any one of a number of methods can determine that these are the values of the polynomial {{{f(n) = n^2+n}}}.<br>
The last number in the 16th equation is then {{{f(16) = 16^2+16 = 256+16 = 272}}}