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Please help! Will mark brainliest

Please Help Will Mark Brainliest class=
Please Help Will Mark Brainliest class=

Sagot :

Answer:

Step-by-step explanation:

t1 = a1

t2 = a1 + d

t3 = a1 + 2d

The sum is t1 + t2 + t3 = a1 + a1 + d + a1 + 2d = 3a1 + 3d

Second question

t1 = a1

t2 = a1 + d

t3 = a1 + 2d

t4 = a1 + 3d

...

tn = a1 + (n - 1)*d

Sum = (a1 + a1 + (n- 1)*d) * n / 2

Sum = (2a1 + nd - d) * n / 2

Sum = (2a1*n + n^2*d - nd) / 2