Question

Difficulty: MediumExponents, Roots, and Scientific Notation

Arrange the following four mathematical expressions in order from least to greatest value:

  1. 1S=(25)2S = \left(\frac{2}{5}\right)^2
  2. 2P=41P = 4^{-1}
  3. 3R=2.8×101R = 2.8 \times 10^{-1}
  4. 4Q=0.09Q = \sqrt{0.09}

Answer

The correct order from least to greatest is SS, PP, RR, and QQ, which correspond to the decimal values 0.16<0.25<0.28<0.30.16 < 0.25 < 0.28 < 0.3.
Evaluating each term yields decimal values: S=0.16S = 0.16, P=0.25P = 0.25, R=0.28R = 0.28, and Q=0.3Q = 0.3. Ordering these from least to greatest gives 0.16<0.25<0.28<0.30.16 < 0.25 < 0.28 < 0.3, which corresponds to the sequence S,P,R,QS, P, R, Q.

Step-by-Step Solution

1
Convert the fractional squared expression SS to a decimal.
S=(25)2=425=0.16S = \left(\frac{2}{5}\right)^2 = \frac{4}{25} = 0.16
Squaring a fraction involves squaring both the numerator and denominator, then converting the resulting fraction to decimal form.
2
Convert the negative exponent expression PP to a decimal.
P=41=14=0.25P = 4^{-1} = \frac{1}{4} = 0.25
A negative exponent represents the reciprocal of the base raised to the positive power.
3
Convert the scientific notation expression RR to a decimal.
R=2.8×101=0.28R = 2.8 \times 10^{-1} = 0.28
Multiplying by 10110^{-1} shifts the decimal point one position to the left.
4
Convert the square root expression QQ to a decimal.
Q=0.09=0.3Q = \sqrt{0.09} = 0.3
Finding the square root of a decimal less than 11 results in a value larger than the original decimal, since 0.3×0.3=0.090.3 \times 0.3 = 0.09.
5
Compare the resulting decimal values to order them from least to greatest.
0.16<0.25<0.28<0.30.16 < 0.25 < 0.28 < 0.3, so the order is S<P<R<QS < P < R < Q.
Ordering the converted decimal values yields the correct final arrangement.

Key Concept

Converting exponential, radical, and scientific notation expressions to decimals to compare and order their values.
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