Sn=n/2 (2a1 +(n-1)d)
[s5= 5/2 (2a1 +(5-1)d) = 5a1+10d]
s6=3(2a1+5d) = 6a1+15d
s4=2(2a1+3d) = 4a1+6d
6a1+15d -(4a1+6d) = 5 -----(1)
s7=7/2(2a1+6d) =7a1+21d
6a1+15d + 7a1+21d = 21 -----(2)
(1) 2a1+9d=5 -----(3)
(2) 13a1+36d=21 ----(4)
(3)*4 ; 8a1+36d=20 ----(5)
(4)-(5) 5a1 = 1
so a1 = 1/5
(3) 2a1+9d=5
2(1/5)+9d = 5
9d = 5-2/5 =23/5
d = 23/45
so [s5= 5/2 (2a1 +(5-1)d) = 5a1+10d = 5(1/5) + 10(23/45) = 1 + 5.11 = 6.11 ]
i'm not sure about the answer but the process is correct
Answer
12x+40
Step-by-step explanation:
when distributing, you have to multiply all numbers in the parentheses by the variable outside the parentheses
Answer:
C y= 3x+2
Step-by-step explanation:
You do 28 / 4 and you get 7, so the answer is 7.
Answer:
60
Step-by-step explanation:
Because 30 is half of 60
Hope this helps. Pls give brainliest.
