Jawapan

  • Pengguna Brainly
2016-02-07T19:33:36+08:00
T3 = 75 , T4 = 375 , S7 - S3 = ?

T3 = 75
75 = a ( r^2)
75 = ar^2
a = 75/r^2

T4 = 375
375 = 75/r^2 ( r^4 - 1 ) / r - 1
375r - 375 = 75r^2 - 75
75r^2 - 375r + 375 - 75 = 0
75r^2 - 375r + 300 = 0
( r - 4 ) ( r - 1 ) = 0
r = 4 (ignore) , r = 1

a = 75/(16)
a = 4.7
a = 5_______ignore

a = 75/1
a = 75

T3 = 75 ( 1^2)
     = 75

S7 - S3 = { 75 ( 1^6 - 1 ) } - { 75 ( 1^2 - 1 ) }
             = 0 - ( 0 )
             = 0
1 5 1