Question

Iliana and Rod were asked to find the difference of (5.1 times 10 Superscript negative 15 Baseline) minus (2.3 times 10 Superscript negative 14 Baseline). As a first step, Iliana rewrote the problem as (0.51 times 10 Superscript negative 14 Baseline) minus (2.3 times 10 Superscript negative 14), and Rod rewrote the problem as (5.1 times 10 Superscript negative 15 Baseline) minus (0.23 times 10 Superscript negative 15 Baseline). Which person wrote a correct possible first step? Why?

Answer 1

Given:

The expression is

$(5.1\times 10^{-15})-(2.3\times 10^{-14})$

First steps of Iliana and Rod are given.

To find:

Which person wrote a correct possible first step.

Solution:

We have,

$(5.1\times 10^{-15})-(2.3\times 10^{-14})$

If we want -15 in the power of 10, then

$(5.1\times 10^{-15})-(2.3\times 10^{-14-1+1})$

$(5.1\times 10^{-15})-(2.3\times 10^{-15}\times 10)$

$(5.1\times 10^{-15})-(23\times 10^{-15})$

Therefore, first step of Rod  is incorrect.

If we want -15 in the power of 10, then

$(5.1\times 10^{-15+1-1})-(2.3\times 10^{-14})$

$(5.1\times 10^{-14}\times 10^{-1})-(2.3\times 10^{-14})$

$(\dfrac{5.1}{10}\times 10^{-14})-(2.3\times 10^{-14})$

$(0.51\times 10^{-14})-(2.3\times 10^{-14})$

Therefore, first step of Iliana is correct.

Answer 2

Answer:

B "Only Iliana is correct because Rod incorrectly equated 2.3 times 10 Superscript negative 14 and 0.23 times 10 Superscript negative 15."

explanation: