Final answer:
To add the numbers in scientific notation, align the exponents and combine the coefficients. The negligible term is ignored, and the result is 6.6×105 in scientific notation to two significant figures.
Step-by-step explanation:
The question involves adding numbers written in scientific notation and providing the answer in standard form to two significant figures. The calculation of 6.4×105 + 1.9×104 + 5.7×10-4 requires careful attention to the exponents of ten to ensure that the values are combined correctly. To perform the addition, align the exponents, combine the coefficients, and then adjust the result back to proper scientific notation if necessary.
First, convert all numbers to the same power of ten if they differ:
6.4×105 is already the largest exponent and remains unchanged.
1.9×104 becomes 0.19×105 when the exponent is increased by 1.
5.7×10-4 becomes negligible when compared with the other large numbers and can be omitted from the two-significant-figure result.
Now, add these together: 6.4 + 0.19 equals approximately 6.6. Since we require two significant figures, we round this to 6.6×105.