Question 76195
if you picture the bridge sitting on the x-axis and centered on the y-axis, then the parabola passes through (-10,0), (0,10), and (10,0)


the parabola has the form {{{y=ax^2+bx+c}}}


substituting (0,10) gives c=10


substituting (-10,0) gives 0=100a-10b+10


substituting (10,0) gives 0=100a+10b+10...adding the previous equation gives 0=200a+20...or a=-.1...so b=0


the equation for the parabola is {{{y=-.1x^2+10}}}...so for x=8(or -8), y=3.6


you can locate the parabola anywhere and it will change the values of constants, but the answer will be the same