Question

find the sum ofthe first 25 multiples of 8

Answer 1

Answer:

Step-by-step explanation:

→ The formula of sum of arithmetic series given the first term and common difference and the number of term.

= n/2 [ 2(a₁) + (n-1) (d)]

→ a₁ = 8    n = 25      d = 8

= 25/2 [ 2(8) + (25-1)(8)]

→ S₂₅ = 25/2 [16 + (24)(8) ]

→ S₂₅ = 25/2 [16 + 192]

→ S₂₅ = 25/2 (208)

→ S₂₅ = 25 (104)

→ S₂₅ = 2,600    

Answer 2

Sum of first 25 multiples of 8

....

8+16+24+32+40+48+56+64+72+80+88+96+104+112+120+128+136+144+152+160+168+176+184+192+200

Take 8 as common

8(1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25)

....

=8(325)

....

=2600

Hope this may help you

Mark as brainliest☺☺☺