You just need to divide 13 and 2 and get 6.5.
Answer:
Sum of the first 15 terms = -405
Step-by-step explanation:
a + 3d = -15 (1)
a + 8d = -30 (2)
Where,
a = first term
d = common difference
n = number of terms
Subtract (1) from (1)
8d - 3d = -30 - (-15)
5d = -30 + 15
5d = -15
d = -15/5
= -3
d = -3
Substitute d = -3 into (1)
a + 3d = -15
a + 3(-3) = -15
a - 9 = -15
a = -15 + 9
a = -6
Sum of the first 15 terms
S = n/2[2a + (n − 1) × d]
= 15/2 {2×-6 + (15-1)-3}
= 7.5{-12 + (14)-3}
= 7.5{ -12 - 42}
= 7.5{-54}
= -405
Sum of the first 15 terms = -405
Answer:
R=7
Step-by-step explanation:
R=1+3w
This is a classic substitution question.
Just replace the w with 2.
R = 1+3(2)
You only need to multiply 3 with 2.
R = 1 + 6
R= 7
I can’t see the picture clearly, but the line should be horizontal and it should be running through -3 on the y axis and the bottom should be highlighted
