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For an arithmetic sequence where a1 = 17 and the common difference is 5, find s7. A. 229 B. 235 C. 224 D. 219 please show steps 11 points

Respuesta :

Thckumms

Answer:

The correct answer is C. 224

Step-by-step explanation:

Sn = n/2 (2*A1 +d(x-1))

S7=7/2(2*17+5(7-1))

S7=7/2(34+30)

S7=7/2(64)

S7=7*64/2

S7=7*32/1

S7=224

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JeanaShupp

Answer: C. 224

Step-by-step explanation:

Given : The first term of an arithmetic sequence = [tex]a_1=17[/tex]

Common difference : [tex]d=5[/tex]

We know that the sum of first n terms is given by :-

[tex]S_n=\dfrac{n}{2}(2a+(n-1)d)[/tex]

Now, for n=7 we have

[tex]S_7=\dfrac{7}{2}(2(17)+(7-1)(5))\\\\\Rightarrow\ S_7=\dfrac{7}{2}(34+30)\\\\\Rightarrow\ S_7=\dfrac{7}{2}(64)\\\\\Rightarrow\ S_7=224[/tex]

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