Question

Difficulty: HardExponents, Roots, and Scientific Notation

If a=2×103a = 2 \times 10^3 and b=3×104b = 3 \times 10^{-4}, what is the value of the expression a3b21.8\sqrt{\frac{a^3 \cdot b^2}{1.8}}?

Answer: 20

Answer

20
Evaluating the components of the expression sequentially: a3=8×109a^3 = 8 \times 10^9 and b2=9×108b^2 = 9 \times 10^{-8}. Multiplying them yields (8×9)×1098=72×101=720(8 \times 9) \times 10^{9-8} = 72 \times 10^1 = 720. Dividing by the decimal 1.81.8 results in 720/1.8=400720 / 1.8 = 400. The square root of 400400 yields 2020.

Step-by-Step Solution

1
Calculate the value of a3a^3
8×1098 \times 10^9
Apply the power of a product rule, (xy)n=xnyn(xy)^n = x^n y^n, and the power of a power rule, (10p)q=10pq(10^p)^q = 10^{p \cdot q}.
2
Calculate the value of b2b^2
9×1089 \times 10^{-8}
Apply the power of a product rule and power of a power rule to (3×104)2(3 \times 10^{-4})^2.
3
Multiply a3a^3 and b2b^2
720720
Multiply the coefficients (8×9=728 \times 9 = 72) and add the exponents of the base 10 (109×108=10110^9 \times 10^{-8} = 10^1), resulting in 72×10=72072 \times 10 = 720.
4
Divide the product by 1.81.8
400400
Substitute the values to get 720/1.8720 / 1.8, which simplifies to 7200/18=4007200 / 18 = 400.
5
Take the square root of the quotient
2020
Find the non-negative square root of 400400, which is 2020.

Key Concept

Simplifying numerical expressions containing combinations of exponent rules, roots, and scientific notation.
Estimated Time:1m 30s
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