Look at the formula for the area of a circle below.
A=a72
Which of the following equations can be used to solve for the radius (r)?

The difference of 2 numbers is 21 and the quotient of the equation is 4 then what are the two numbers?

Xto the second power plus 14x plus 48. what are the factors? we are doing factoring trinomials with a=1

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.