I NEED HELP WITH THIS ITS WORTH 100 POINTS PLEASE HELP ME

Solve the equation by completing the square. x^2+2x=17

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.

Lana's family entered a 5-kilometer race lana's average step length is about 0.5 meter how many steps will she need to take the finish