Question

Which of these is correct?(1 point)
Responses

(9.9×107)(5.8×106)=5.72×1013
open paren 9 point 9 times 10 to the 7th power close paren times open paren 5 point 8 times 10 to the 6th power close paren is equal to 5 point 7 2 times 10 to the 13th power

(4.6×105)(2.1×104)=2.5×10
(4.6×105)(2.1×104)=2.5×10

(2.9×108)(1.3×107)=3.77×1015
open paren 2 point 9 times 10 to the 8th power close paren times open paren 1 point 3 times 10 to the 7th power close paren is equal to 3 point 7 7 times 10 to the 15th power

(8.8×108)(4.2×107)=13×1015
open paren 8 point 8 times 10 to the 8th power close paren times open paren 4 point 2 times 10 to the 7th power close paren is equal to 13 times 10 to the 15th power

Answer 1

Only the third one is correct.

Work:
1) (9.9×10^7)(5.8×10^6) = 57.42×10^13 = 5.742×10^14 (not 5.72×10^13) — incorrect.
2) (4.6×10^5)(2.1×10^4) = 9.66×10^9 (not 2.5×10) — incorrect.
3) (2.9×10^8)(1.3×10^7) = 3.77×10^15 — correct.
4) (8.8×10^8)(4.2×10^7) = 36.96×10^15 = 3.696×10^16 (not 13×10^15) — incorrect.