document.write( "Question 16536: if (a+2)x^2- 2ax - a = 0
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Algebra.Com's Answer #8082 by AnlytcPhil(1810)\"\" \"About 
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\n" ); document.write( "if (a+2)x^2- 2ax - a = 0
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\n" ); document.write( "what is range of a ?
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\n" ); document.write( "If you were to solve this problem by the quadratic formula,
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\n" ); document.write( "A = (a+2), B = -2a, C = -a
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\n" ); document.write( "the expression underneath the square root, B2 - 4AC, known as the
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\n" ); document.write( "` ` ` ` ` `B2 - 4AC >= 0
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\n" ); document.write( "(-2a)2 - 4(a+2)(-a) >= 0
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\n" ); document.write( "` ` ` 4a2 + 4a(a+2) >= 0
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\n" ); document.write( "` ` `4a2 + 4a2 + 8a >= 0
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\n" ); document.write( "` ` ` ` ` `8a2 + 8a >= 0
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\n" ); document.write( "` ` ` ` ` 8a(a + 1) >= 0
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\n" ); document.write( "The zeros of the left side are 0 and -1
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\n" ); document.write( "Make a number line, and mark these solid since they are solutions.
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\n" ); document.write( "-4 -3 -2 -1 `0 +1 +2 +3 +4
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\n" ); document.write( "Choose any value in the leftmost region, the region left of -1. The easiest
\n" ); document.write( "value to choose is -2. Substitute it into the expression
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\n" ); document.write( "8a(a + 1)
\n" ); document.write( "8(-2)(-2 + 1) = -16(-1) = +16. This is nonnegative, so shade all those values.
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\n" ); document.write( "`-4 -3 -2 -1 0 +1 +2 +3 +4
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\n" ); document.write( "Choose any value in the middle region, the region between -1 and 0. The
\n" ); document.write( "easiest value to choose is -1/2. Substitute it into the expression
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\n" ); document.write( "8a(a + 1)
\n" ); document.write( "8(-1/2)(-1/2 + 1) = -4(1/2) = -2. This is negative, so do not shade the values
\n" ); document.write( "in the middle region.
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\n" ); document.write( "Choose any value in the rightmost region, the region right of 0. The easiest
\n" ); document.write( "value to choose is 1. Substitute it into the expression
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\n" ); document.write( "8a(a + 1)
\n" ); document.write( "8(1)(1 + 1) = 8(2) = +16. This is nonnegative, so shade all those values.
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\n" ); document.write( "`-4 -3 -2 -1 `0 +1 +2 +3 +4
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\n" ); document.write( "The interval notation for this is
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\n" ); document.write( "Edwin
\n" ); document.write( "AnlytcPhil@aol.com
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