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:
oop xc
Step-by-step explanation:
Answer:
11) I haven't done these yet don't go by my answers wait for more responses.
So if TR looks exactly half way from the middle and it says its 11, and if PS is basically two of TR then it would be 22. It looks to me that TR is 11 which is exactly half way I think, and PS looks double of TR so 2 x 11 = 22. Please go by the way you learned i don't know if I'm right.
12) If MK is exactly straight and its 10, half of 10 would be 5. I did half of 10 because L to M looks as if it is 10 already but since its L to the point in the middle that would be half way of the total line from L to M. So L to the point must be 5, MK is already given which is 10 so now we add 5 since L to the point in the middle is half way of 10 which is 5.
10(MK) + 5(L to the point in the middle of the circle) = 15
I don't want to be the one who brings your grades down so do by the way you learned.
