document.write( "Question 230804: find the y-intercept of a parabola whose vertex is (-1,2), which is turned downward, and whose width is the same as y=2x^2. \n" ); document.write( "
Algebra.Com's Answer #171231 by ankor@dixie-net.com(22740)\"\" \"About 
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find the y-intercept of a parabola whose vertex is (-1,2), which is turned
\n" ); document.write( " downward, and whose width is the same as y = 2x^2.
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\n" ); document.write( "Using the form ax^2 - bx + c = y
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\n" ); document.write( "We know the axis of symmetry; x = -1, and a=2
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\n" ); document.write( "use the axis of symmetry formula to find b; x = -b/(2*a)
\n" ); document.write( "-1 = \"%28-b%29%2F%282%2A2%29\"
\n" ); document.write( "-1 = \"%28-b%29%2F4\"
\n" ); document.write( "4(-1) = -b
\n" ); document.write( "-4 = -b
\n" ); document.write( "b = +4
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\n" ); document.write( "We have 2x^2 + 4x + c = y
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\n" ); document.write( "when x=-1, y=2
\n" ); document.write( "2(-1)^2 + 4(-1) + c = 2
\n" ); document.write( "2(1) - 4 + c = 2
\n" ); document.write( "2 - 4 + c = 2
\n" ); document.write( "-2 + c = 2
\n" ); document.write( "c = 2 + 2
\n" ); document.write( "c = 4
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\n" ); document.write( "equation: y = 2x^2 + 4x + 4; therefore, the y intercept = 4
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\n" ); document.write( "looks like this:
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-6%2C+5%2C+-10%2C+10%2C+2x%5E2%2B4x%2B4%29%29+\"
\n" ); document.write( "Vertex -1,2; y intercept +4
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