21. Which of the following is the factored form of \( 81 x - 36 y \) ? ₹ FinD GCF + Use Distributive Property
A. \( 3 ( 27 x - 12 y ) \)
B. \( 9 ( 9 x - 4 y ) \)
C. \( ( 9 \cdot 9 ) \cdot x - ( 9 \cdot 4 ) \cdot y \)
D. \( 9 ^ { 2 } \cdot x - 6 ^ { 2 } \cdot y\)
B
Find the solution of the exponential equation \( 16 e ^ { x } = 12 \) in terms of logarithms, or correct to four decimal places. \( x = \)
Certain radioactive material decays in such a way that the mass remaining after \( t \) years is given by the function
\( m ( t ) = 100 e ^ { - 0.01 t } \)
where \( m ( t ) \) is measured in grams. (a) Find the mass at time \( t = 0 \) . Your answer is (b) How much of the mass remains after \( 20 \) years? Your answer is Round answers to \( 1 \) decimal place.
