ocr: The sequence is 6,-2,-10,-18, : Touse the tormula an = 21 +(n-1)a, you need 21 whichis 6; - n, which will be given; and d. d=an-a an-1 --18-(-10)--18+10--8 Term number Qn : =01 +(n-1)d Term 5 as =6+( 5-1)(-8) -26 6 26-6+( 6-1)(-8) -34 10 210 =6+( - 10 -1)(-8) -66 50 250 - = 6+( - - - 50 -1)(-8) -386 100 2100 = 6+( 100-1)(-8) -786 1000 21000 = 6+(1000-1)(-8) -7986 Arithmetic and Geometric Sequences
