The additive property of zero states that when you have any number and add zero to it, your answer will always equal the original number
<span> 5×-(3+9)
Substitute 6 for x
5(6)-(3+9)
Add 9 to 3
5(6)-12
Multiply 5 by 6
30-12
Final Answer: 18</span>
Answer: Olga's solution is incorrect
x + 7x is the same as 1x + 7x
7x2 is the same as 7x. x
x + 7 x simplifies to 8x
Step-by-step explanation:
Remember that c is the initial height. Since we the rocket is in a 99-foot cliff, c=99. Also, we know that the velocity of the rocket is 122 ft/s; therefore v=122
Lets replace the values into the the vertical motion formula to get:

Notice that the rocket hits the ground at the bottom of the cliff, which means that the final height is 99-foot bellow its original position; therefore, our final height will be h=-99
Lets replace this into our equation to get:


Now we can apply the quadratic formula

where a=-16, b=122, and c=198


or


or


or

Since the time can't be negative, we can conclude that the rocket hits the ground after 9 seconds.