Answer: A. He changed the sign of the coefficient. A negative exponent does not affect the sign of a coefficient in scientific notation. The sign of the exponent determines the direction the decimal is moved in.
B. He rewrote incorrectly; . The exponent is increased to account for the extra place the decimal is moved.
Step-by-step explanation:
Given expression :
[Taking coefficients and exponents separate]
[By law of exponent]
Here he changed the sign of the coefficient. A negative exponent does not affect the sign of a coefficient in scientific notation. The sign of the exponent determines the direction the decimal is moved in.
Convert in scientific form.
In the given explanation he rewrote incorrectly; . The exponent is increased to account for the extra place the decimal is moved.
Thus, option A and B express the errors done by Stephen.