document.write( "Question 258096: how do i solve 4x^2+4x-15=0 \n" ); document.write( "

Algebra.Com's Answer #189951 by checkley77(12844) $\"\"$ $\"About$

You can put this solution on YOUR website!
The factors of the a term(4x) are: 1*4 & 2*2
\n" ); document.write( "The factors of the term(-15) are -1*15, 1*-15, -3*5, 3*-5
\n" ); document.write( "Now the secret is to find the sum of the products that = 4
\n" ); document.write( "1*-1+4*15=-1+60=59 reject
\n" ); document.write( "1*15+4*-1=15-4=11 reject
\n" ); document.write( "1*1+4*-15=1-60=-59 reject
\n" ); document.write( "1*-15+4*4=-15+15=31 reject
\n" ); document.write( "1*-3+4*5=-3+20=17 reject
\n" ); document.write( "1*5+4*-3=5-12=-7 reject
\n" ); document.write( "1*3+4*-5=3-20=-17 reject
\n" ); document.write( "2*-1+2*15=-2+30=28 reject
\n" ); document.write( "************************************
\n" ); document.write( "2*-3+2*5=-6+10=4 eureka.
\n" ); document.write( "Proof:
\n" ); document.write( "Using the FOIL system.
\n" ); document.write( "2x*2x+2x*5-3x*2-3*5
\n" ); document.write( "4x*2+10x-6x-15
\n" ); document.write( "[4x^2+4x-15]
\n" ); document.write( "*************************************
\n" ); document.write( "2*3+2*-5=6-10-4 reject
\n" ); document.write( "------------------------------
\n" ); document.write( "4x^2+4x-15=0
\n" ); document.write( "(2x-3)(2x+5)=0
\n" ); document.write( "2x-3=0
\n" ); document.write( "2x=3
\n" ); document.write( "x=3/2
\n" ); document.write( "x=1.5 ans.
\n" ); document.write( "2x+5=0
\n" ); document.write( "2x=-5
\n" ); document.write( "x=-5/2
\n" ); document.write( "x=-2.5 ans. \n" ); document.write( "

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