<PRE><B>Question 1185343</B>
&lt;br&gt;
The definition&lt;br&gt;
{{{u(n+1)=u(n)+4}}}&lt;br&gt;
means each term is 4 more than the preceding term.&lt;br&gt;
You are given u(1)=10, so the sequence is&lt;br&gt;
10, 14, 18, 22, ...&lt;br&gt;
The problem asks for the sum of the first 20 terms.&lt;br&gt;
-----------------------------------------------------------------&lt;br&gt;
With a common difference of 4 between successive terms, the sequence is arithmetic.&lt;br&gt;
The sum of any set of numbers is the number of numbers, multiplied by the average of the numbers.&lt;br&gt;
In an arithmetic sequence, because of the common difference between terms, the average of all the terms is the average of the first and last terms.&lt;br&gt;
The last (20th) term is the first term 10, plus the common difference 19 times:  u(20)=10+19(4)=86&lt;br&gt;
So the sum of the first 20 terms in this sequence is the number of terms (20), multiplied by the average of the first and last terms ((10+86)/2=48).&lt;br&gt;
ANSWER: 20*48 = 960&lt;br&gt;
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