Let's evaluate each expression step by step.
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(9.9 × 10^7)(5.8 × 10^6):
- Coefficients: \(9.9 \times 5.8 = 57.42\)
- Exponents: \(10^7 \times 10^6 = 10^{7+6} = 10^{13}\)
- Result: \(57.42 \times 10^{13}\), which can be expressed as \(5.742 \times 10^{14}\) (after adjusting the coefficient).
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(2.9 × 10^8)(1.3 × 10^7):
- Coefficients: \(2.9 \times 1.3 = 3.77\)
- Exponents: \(10^8 \times 10^7 = 10^{15}\)
- Result: \(3.77 \times 10^{15}\). This is correct.
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(8.8 × 10^8)(4.2 × 10^7):
- Coefficients: \(8.8 \times 4.2 = 37.76\)
- Exponents: \(10^8 \times 10^7 = 10^{15}\)
- Result: \(37.76 \times 10^{15}\), which can be expressed as \(3.776 \times 10^{16}\) (after adjusting the coefficient). Thus, it's incorrect as the provided answer is \(13 \times 10^{15}\).
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(4.6 × 10^5)(2.1 × 10^4):
- Coefficients: \(4.6 \times 2.1 = 9.66\)
- Exponents: \(10^5 \times 10^4 = 10^{9}\)
- Result: \(9.66 \times 10^{9}\), which is not equal to \(2.5 \times 10\).
In summary, the only correct statement among the options provided is:
(2.9 × 10^8)(1.3 × 10^7) = 3.77 × 10^15.