document.write( "Question 389917: Find the x-intercept of the parabola with vertex (-3,-18)and y-intercept(0,0). \n" ); document.write( "

Algebra.Com's Answer #276632 by lwsshak3(11628) $\"\"$ $\"About$

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Standard form of the parabola,
\n" ); document.write( "y=A(x-h)^2 +k, (h,k) representing the (x,y) coordinates of the vertex
\n" ); document.write( "with given (h,k) = (-3,-18)
\n" ); document.write( "y=A(x+3)^2 -18
\n" ); document.write( "solving for A, using a given (x,y) point,(0,0) of the parabola,
\n" ); document.write( "0=A(0+3)^2-18
\n" ); document.write( "9A=18
\n" ); document.write( "A=2
\n" ); document.write( "equation of the parabola: y=2(x+3)^2-18
\n" ); document.write( "in another form, y=2(x^2+6x+9)-18
\n" ); document.write( "=2x^2+12x+18-18
\n" ); document.write( "=2x^2+12x=2x(x+6)
\n" ); document.write( "to find x-intercepts,set y=0
\n" ); document.write( "2x(x+6) =0
\n" ); document.write( "2x=0
\n" ); document.write( "x=0
\n" ); document.write( "x+6=0
\n" ); document.write( "x=-6\r
\n" ); document.write( "\n" ); document.write( "ans: parabola intercepts x-axis at 0 and -6
\n" ); document.write( "see graph below\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " $\"+graph%28+300%2C+200%2C+-6%2C+5%2C+-20%2C+10%2C+2%28x%2B3%29%5E2-18%29+\"$ \n" ); document.write( "

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