Respuesta :

Answer:

first term a1 is -40.

Step-by-step explanation:

in an arithmetic series,

sum of first term terms (S10) = -20

Common difference (d) = 4

first term (a)= ?

number of terms (n)= 10

now,

S10 =( n÷2) [a1 +(n-1) d]

or, -20 = (10÷2) [a1 + (10-1) 4]

or, -20 = 5 ( a1 + 36)

or, -4 = a1 + 36

or, a1 = -40

Step-by-step explanation:

[tex] \green\star[/tex] Given

[tex]\blue\star[/tex]s10 = -20

[tex]\blue\star[/tex]n = 10

[tex]\blue\star[/tex] an = -20

[tex] \green\star[/tex] solution

[tex] \green\star[/tex]s10 = n\2 [a+(n-1)d]

[tex] \green\star[/tex]-20 = 10a2[a+(10-1)4]

[tex] \green\star[/tex]-4 = a +36

[tex] \green\star[/tex]a1 = -40

[tex]\small\boxed{a = -40}[/tex]

Hope it helps.

Hope it helps

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