document.write( "Question 760887: f(x)=x^2-4x-5 i need help finding y intercept, x intercept, vertex, and axis of symmetry i am not grasping how to get the answer even after looking over other examples.. \n" ); document.write( "

Algebra.Com's Answer #462901 by Cromlix(4381) $\"\"$ $\"About$

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f(x) = x^2 - 4x - 5
\n" ); document.write( "Factorise
\n" ); document.write( " (x - 5)(x + 1) = 0
\n" ); document.write( " x - 5 = 0
\n" ); document.write( " x = 5
\n" ); document.write( " x + 1 = 0
\n" ); document.write( " x = -1
\n" ); document.write( "This where the parabola cuts the x axis (-1,0) and (5,0)
\n" ); document.write( "f(x) = x^2 - 4x - 5
\n" ); document.write( "To find where it cuts the y axis make x = 0
\n" ); document.write( " f(0) = 0^2 -4(0) - 5
\n" ); document.write( " So parabola cuts y axis at (0, -5)
\n" ); document.write( "To find the vertex.
\n" ); document.write( "The distance between x = -1 and x = 5
\n" ); document.write( "(where it cuts the x axis) is 6 units
\n" ); document.write( "Half of 6 = 3
\n" ); document.write( "So either add 3 to -1 = 2
\n" ); document.write( " or subtract 3 from 5 = 2
\n" ); document.write( "Now this shows that the axis of symmetry is
\n" ); document.write( " x = 2
\n" ); document.write( "Now put x =2 into the equation
\n" ); document.write( "f(x) = x^2 - 4x - 5
\n" ); document.write( " = (2)^2 - 4(2) - 5
\n" ); document.write( " = 4 - 8 - 5
\n" ); document.write( " = -9
\n" ); document.write( "This is the y coordinate of the vertex
\n" ); document.write( " (2, -9)
\n" ); document.write( "I hope this helps you.
\n" ); document.write( ":-) \n" ); document.write( "

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