Week 1 – Arithmetic Sequence

Arithmetic Sequence; 7,14,21,28,35

Finding $t_{n}$ ;

$t_{n}$ = $t_{1}$ + (n-1) d

$t_{n}$ = 7 + (7n-7)

$t_{n}$ = 7n

Finding $t_{50}$ ,

$t_{50}$ = $t_{1}$ + (n-1) d

$t_{50}$ = 7 + (50-1) 7

$t_{50}$ = 7 + (49) 7

$t_{50}$ = 7 + 343

$t_{50}$ = 350

Finding $s_{50}$ ;

$s_{50}$ = $\frac{n}{2}$ ( 2 $t_{1}$ n – 1 ) d

$s_{50}$ = $\frac{50}{2}$ ( 14 + (50-1) 7 )

$s_{50}$ = 25 ( 14 + (49) 7 )

$s_{50}$ = 25 ( 14 + 343 )

$s_{50}$ = 25 ( 357 )

$s_{50}$ = 8925

Cameron's Blog