Question

- If A = 1 - 10 +3 - 12 + 5 - 14 + 7 + ... upto 60 terms, then what is the value of A?​

Answer 1

Answer:

Short

Subtract consecutive terms

A = (1-10) + (3 - 12)+ ( 5-14)..........60terms

A = -9 + (-9) + (-9)...........30terms

A = -9 × 30 = -270

Long way

There is two mixed Arithmetic series , separate them

A = ( 1 + 3 + 5......30terms ) - ( 10 + 12 + ....30terms)

Use formula of sum .

Answer 2

Answer:

A=270

Step-by-step explanation:

A=1-10+3-12+5-14+.....upto 60 terms.

A=(1+3+5+7.....30 terms)-(10+12+14.....30 terms.)

A=15[2+(30-1)2]-15[20(30-1)2]

A=15(60)-15(78)

A=-270

THANKS

KHUSHI