⚠️HELP⚠️ If <6≈<10and <5≈<7, which describes all the lines that must be parallel?

o Only lines r and s must be parallel.
o Only lines t and umust be parallel.
Lines r and s and lines t and u must be parallel.
O Neither lines r and s nor lines t and u must be parallel

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

1. evaluate 8x(2)y9(-2) for x=-1 and y=2 2. simplify the equation. -() 3. simplify the expression. [tex]\frac{5}{x(-2) y9(5)}[/tex]

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.