If the sequence a is arithmetic, and a_3 = 5, and a_5 = 15, find a_9.
2007-05-21 13:12:35 · 5 answers · asked by hankypanky680 1 in Science & Mathematics ➔ Mathematics
a_9 = 35
a_3 = 5
a_4 = 10
a_5 = 15
a_6 = 20
a_7 = 25
a_8 = 30
a_9 = 35
2007-05-21 13:16:05 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The answer would be a_9=35 because the common diffrence between the answer a_3 and a_5 is 5 so line it up as a pattern adding 5 every time. Ex.
a_3=5
a_4=10
a_5=15
a_6=20
a_7=25
a_8=30
a_9=35
2007-05-21 20:26:05 · answer #2 · answered by harleymeagan 2 · 0⤊ 0⤋
We know that a_n=a_0+(n-1)d
So, we are trying to find d.
Change a_3 to a_1, change a_5 to a_3 and change a_9 to a_7.
a_n=15 and n=3
So,
15=5+(3-1)d
d=5
Now we know d, so we want to find a_7.
a_7=5+(7-1)(5)
a_7=35
Change the a_7 back to a_9=35
I hope that this helps
2007-05-21 20:19:39 · answer #3 · answered by unhrdof 3 · 0⤊ 0⤋
a9 = 35
The common difference is 5.
2007-05-21 20:17:16 · answer #4 · answered by ironduke8159 7 · 0⤊ 0⤋
d = 5
a_9 = 35
2007-05-21 20:15:45 · answer #5 · answered by richardwptljc 6 · 0⤊ 1⤋