Que propiedad justifica que 4+[6+(-2)]=[4+6]+(-2)

If the discriminant if a quadratic equation is 4 which statement describes the roots?

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.

Elm street is straight. willard's house is at point h between the school at point s and the mall at point m. if sh = 3 miles and hm = 4.5 miles, what is the value of sm in miles?