Answer:49Step-by-step explanation:I think I have read this right!You let me know if you did not mean to write the following:[tex]\sum_{k=1}^{7}(1+(k-1)(2)[/tex]Alright so the lower limit is 1 and the upper limit is 7.All this means is we are going to use the expression 1+(k-1)(2) and evaluate it for each natural number between k=1 and k=7 and at both k=1 and k=7.The sigma thing means we add those results.So let's start.Evaluating the expression at k=1: 1+(1-1)(2)=1+(0)(2)=1+0=1.Evaluating the expression at k=2: 1+(2-1)(2)=1+(1)(2)=1+2=3.Evaluating the expression at k=3: 1+(3-1)(2)=1+(2)(2)=1+4=5.Evaluating the expression at k=4: 1+(4-1)(2)=1+(3)(2)=1+6=7.Evaluating the expression at k=5: 1+(5-1)(2)=1+(4)(2)=1+8=9.Evaluating the expression at k=6: 1+(6-1)(2)=1+(5)(2)=1+10=11.Evaluating the expression at k=7: 1+(7-1)(2)=1+(6)(2)=1+12=13.Now for the adding!1+3+5+7+9+11+13 4+ 12+ 20+13 16+ 33 49