document.write( "Question 60013: help on this graph needed, please!
\n" ); document.write( "For the quadratic function y= f(x)= x^2-2x-15, find the vertex and x and y intercepts. Sketch the graph, and state the domain and range.
\n" ); document.write( "thanks again, carol
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Algebra.Com's Answer #41219 by funmath(2933)\"\" \"About 
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Hi Carol,
\n" ); document.write( ":
\n" ); document.write( "For the quadratic function y= f(x)= x^2-2x-15, find the vertex and x and y intercepts. Sketch the graph, and state the domain and range.
\n" ); document.write( ":
\n" ); document.write( "You can find the x coordinate of the vertex of a parabola when the quadratic equation is in the form of \"y=f%28x%29=ax%5E2%2Bbx%2Bc\", with the formula \"highlight%28x=-b%2F2a%29\"
\n" ); document.write( "Your a=1, b=-2, and c=-15
\n" ); document.write( "\"x=-%28-2%29%2F%282%281%29%29\"
\n" ); document.write( "\"x=2%2F2\"
\n" ); document.write( "\"x=1\"
\n" ); document.write( "You can find the y coordinate by letting x=1 and solving for y.
\n" ); document.write( "\"y=%281%29%5E2-2%281%29-15\"
\n" ); document.write( "\"y=1-2-15\"
\n" ); document.write( "\"y=-16\"
\n" ); document.write( "The vertex is (1,-16)
\n" ); document.write( ":
\n" ); document.write( "You can find the x-intercepts, if there are any, by letting y=0 and solve for x. This time you can factor, sometimes you have to use the quadratic formula.
\n" ); document.write( "\"0=x%5E2-2x-15\"
\n" ); document.write( "0=(x-5)(x+3)
\n" ); document.write( "x-5=0 and x+3=0
\n" ); document.write( "x-5+5=0+5 and x+3-3=0-3
\n" ); document.write( "x=5 and x=-3
\n" ); document.write( "The x intercepts are (-3,0) and (5,0)
\n" ); document.write( ":
\n" ); document.write( "You can find the y-intercept by letting x=0:
\n" ); document.write( "\"y=%280%29%5E2-2%280%29-15\"
\n" ); document.write( "\"y=0-0-15\"
\n" ); document.write( "\"y=-15\"
\n" ); document.write( "The y-intercept is (0,-15)
\n" ); document.write( "The graph looks like this:
\n" ); document.write( "\"graph%28300%2C200%2C-10%2C10%2C-20%2C5%2Cx%5E2-2x-15%29\"
\n" ); document.write( "Happy Calculating!!!
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