The equation 
describes the height (in feet) of a projectile 
seconds after it is launched from the surface of Mars at 
feet per second. In how many seconds will the projectile first reach 
feet in height? Express your answer as a decimal rounded to the nearest tenth.
+15000 y=-6t^2+43t
In how many seconds will the projectile first reach 77 feet in height?
Hello Guest!
\(77=6t^2+43t\\ -6t^2+43t-77=0\ |\ /(-6)\\ t^2-\frac{43}{6}+\frac{77}{6}=0\\ t=\frac{43}{12}\pm \sqrt{(\frac{43}{12})^2-\frac{77}{6}}\\ \color{blue}t\in \{3.5,3.\overline 6\}\)
In 3.5 seconds will the projectile first reach 77 feet in height.
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