document.write( "Question 118655: What are all possible values of b if 2x^2 +bx= -8 has a discriminant of -15 ? I said 7 but I got it wrong. I don't know how to solve this , can someone please help me ? \n" ); document.write( "
Algebra.Com's Answer #86784 by ankor@dixie-net.com(22740)\"\" \"About 
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\n" ); document.write( "What are all possible values of b if 2x^2 + bx = -8 has a discriminant of -15 ?
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\n" ); document.write( "Put equation in the: y = ax^2 + bx + c; form
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\n" ); document.write( "I think you know how to solve it, you just forgot 1 little thing:
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\n" ); document.write( "y = 2x^2 + bx + 8
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\n" ); document.write( "a = 2; c = 8; find b
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\n" ); document.write( "The discriminant: b^2 - 4*a*c
\n" ); document.write( "In this problem
\n" ); document.write( "b^2 - (4 * 2 * 8) = -15
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\n" ); document.write( "b^2 - 64 = -15
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\n" ); document.write( "b^2 = -15 + 64
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\n" ); document.write( "b = +/-Sqrt(49)
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\n" ); document.write( "b = +/-7 (plus or minus 7 is probably what they wanted you to say.)
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\n" ); document.write( "you can see that 7^2 and -7^2 will have the same value for b^2\r
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\n" ); document.write( "y = 2x^2 + 7x + 8
\n" ); document.write( "and
\n" ); document.write( "y = 2x^2 - 7x + 8 \n" ); document.write( "
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