Question 212980
Find the vertex of the parabola


{{{y=x^2-8x-5}}}


vertex (?,?)


Let's graph this parabola:



Try this set of  x=-2, -1, 0, 1, 2 and substitute into parabola equation.


For example, x=-2, y=(-2)^2-8(-2)-5= 4+16-5=15  point on graph is (-2,15)


One more and then you try, x=0, y=(0)^2-8(0)-5=-5 point on graph is (0,5)


{{{graph( 300, 300, -10, 10, -25, 20,y=x^2-8x-5 )}}}


Based on the graph the vertex is (4, -21)  


Note when we substitute x=4 in


{{{y=x^2-8x-5}}}


{{{y=4^2-8(4)-5=16-32-5=-21}}}


I hope the above steps were helpful.


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Good luck in your studies!


Respectfully,
Dr J