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3 years ago

Find a1 and d for an arithmetic sequence with these terms. a3=-8 and a7=32

1 answer:

4 0

We know that
the formula for the arithmetic sequence is
an = a1 + (n - 1)*d
where
a1 is the first term
n is the numbers of terms

for n=3 a3=-8
-8=a1+(3-1)*d-----> -8=a1+2*d-----> equation 1

for n=7 a7=32
-32=a1+(7-1)*d----> -32=a1+6*d----> equation 2

multiply equation 2 by -1-----> 32=-a1-6*d------> equation 3

add equation 1 and equation 3
-8=a1+2*d
32=-a1-6*d
----------------
24=-4*d------> d=-6
-8=a1+2*(-6) (substitute the value of d in equation 1)
-8=a1-12-----> a1=-8+12-----> a1=4

the answer is
a1=4
d=-6

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4 years ago

Read 2 more answers

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$y=-\frac{1}{2}x+\frac{5}{2}$

Step-by-step explanation:

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I added another image that shows how to graph an equation using the equation y=mx+b

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Answer:

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