Newton's 1st law of motion states that a moving object will go in a straight line unless an outside force changes this motion. what outside force prevents the planets from moving in a straight line into space?

Gravity holds the planets in their orbits. 

All objects in space (and everywhere else!) pull each other. This is called gravity. The reason things don't travel in a straight line through space is because everything is pulling each other with gravity.

The answer is    (d) 7/2======we have    we also  have an integral      notice how function f splits up at x = 0. there's a left piece and a right pieceso we'll need to do the same thing with our integral: split it at x = 0we use a property of integrals that allows us to split up and sum:     notice that for the piecewise function f, the function has the equationf(x) = x when x  ≤ 0. so for the integral  , f(x) = x so it changes into      for the piecewise function f, the function has the equationf(x) = x+1  when x  > 0. for the integral  , we have    therefore, back to our splitted integral: