Question 9 of 20 : select the best answer for the question. 9. –2x(–3x 2y)(2y) = ? a. 12x3y2 b. –3xy2 c. 3xy2 d. –12x3y2

The hawaiian alphabet has 12 letters. how many permutations are posible for each number of letters?

3x + 4y = 5 x- 3y = -7 solve by substitution

Aspacecraft can attain a stable orbit 300 kilometers above earth if it reaches a velocity of 7.7 kilometers per second. the formula for a rocket's maximum velocity v in kilometers per second is vequalsminus0.0098tplusc ln upper r, where t is the firing time in seconds, c is the velocity of the exhaust in kilometers per second, and r is the ratio of the mass of the rocket filled with fuel to the mass of the rocket without fuel. find the velocity of a spacecraft whose booster rocket has a mass ratio of 20, an exhaust velocity of 2.1 km/s, and a firing time of 15 s. can the spacecraft achieve a stable orbit 300 km above earth?