Answer:
The spaceship is at a height 9 feet above the ground at 1 second and 9 second after lunched.
Step-by-step explanation:
Given that a spaceship launched into the air has a height at any time as
[tex]h=-t^2+10t[/tex]
where h is height in feet and t is time in second.
To find the time when the height of the spaceship is 9, we need to put h=9 in the given equation.
[tex]\therefore 9=-t^2+10t[/tex]
[tex]\Rightarrow t^2-10t+9=0[/tex]
[tex]\Rightarrow t^2-9t-t+9=0[/tex]
[tex]\Rightarrow t(t-9)-1(t-9)=0[/tex]
[tex]\Rightarrow (t-9)(t-1)=0[/tex]
[tex]\Rightarrow t=1,9[/tex]
The spaceship is at a height 9 feet above the ground at 1 second and 9 second after lunched.
