Question

A large asteroid crashed into a moon of a planet, causing several boulders from the moon to be propelled into space toward the planet. Astronomers were able to measure the speed of one of the projectiles. The distance (in feet) that the projectile traveled each second, starting with the first second, was given by the arithmetic sequence 29, 40, 51, 62, . . . Find the total distance that the projectile traveled in seven seconds.

339 feet
405 feet
434 feet
182 feet

Answer 1

i think its a but i'm not sure...

Answer 2

use the formula

Sn = n(2a1 + d(n-1))/2

where in this case

a1 = 29 (first term)
d = 11 (common difference)
n = 7 (number of terms you want to sum)

Answer 3

I TRIED TO DERIVE ALL OF MATHEMATICS BUT FAILED...

Answer 4

I am still very confused...

Answer 5

Sn = n(2a1 + d(n-1))/2

S7 = 7*(2*29 + 11(7-1))/2

S7 = ???

Answer 6

434

Answer 7

yep

Answer 8

Thank you :)

Answer 9

you're welcome