document.write( "Question 29250: Can someone pls help me with Simplifying Rational Expressions?, thanks!\r
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Algebra.Com's Answer #16075 by sdmmadam@yahoo.com(530)\"\" \"About 
You can put this solution on YOUR website!
Can someone pls help me with Simplifying Rational Expressions?, thanks! \r
\n" ); document.write( "\n" ); document.write( "1) (3a^2+15a)/(a^3-25a)
\n" ); document.write( "= [3a(a+5)]/[a(a^2-5^2)]
\n" ); document.write( "=3(a+5)/[(a+5)(a-5)] (canceling a)
\n" ); document.write( "(using formula (a^2-b^2)= (a+b)(a-b), here a is a and b =5)
\n" ); document.write( "=3/(a-5)(canceling(a+5)
\n" ); document.write( "Answer:(3a^2+15a)/(a^3-25a)=3/(a-5)\r
\n" ); document.write( "\n" ); document.write( "2)(2x^2-14x)/(x^2-10x+21)
\n" ); document.write( "=[2x(x-7)]/[(x-7)(x-3)]
\n" ); document.write( "=2x/(x-3) (cancel.. (x-7)
\n" ); document.write( "Answer:(2x^2-14x)/(x^2-10x+21)= 2x/(x-3)
\n" ); document.write( "Note: Since the nr contains the factor (x-7), usually the trick of assuming one factor in the dr as (x-7) and later trying the next factor and see if it works is one of the short cuts that will work at times!
\n" ); document.write( "Note: (x^2-10x+21)
\n" ); document.write( "= x^2+(-7x-3x)+21
\n" ); document.write( "= (x^2-7x)-3x+21
\n" ); document.write( "= x(x-7)-3x+21
\n" ); document.write( "= x(x-7)-3(x-7)
\n" ); document.write( "=xp-3p Where p=(x-7)
\n" ); document.write( "=p(x-3)
\n" ); document.write( "= (x-7)(x-3)
\n" ); document.write( "[(splitting the middle term as a sum of two terms in such a way that their product is the product of the square term and the constant term)
\n" ); document.write( "And so, -10x = (-7x) +(-3x) and (-7x)X(-3x) = +21x^2 = (x^2)X(21)]\r
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\n" ); document.write( "\n" ); document.write( "3) (1-3x)/(3x^2+14x-5)
\n" ); document.write( "=(1-3x)/[(x+5)(3x-1)]
\n" ); document.write( "=-(3x-1)/[(x+5)(3x-1)]
\n" ); document.write( "(pulling out (-1) in the nr so as to get (3x-1) same as that in the dr)
\n" ); document.write( "=-1/(x+5) (cancel..(3x-1) )
\n" ); document.write( "Answer:(1-3x)/(3x^2+14x-5)=-1/(x+5)
\n" ); document.write( "Note: take the quadratic expression (3x^2+14x-5)in the rough work column
\n" ); document.write( "and factorise it as follows:
\n" ); document.write( "(3x^2+14x-5)
\n" ); document.write( "=3x^2+(15x-x)-5
\n" ); document.write( "splitting the middle term as a sum of two terms in such a way that their product is the product of the square term and the constant term)
\n" ); document.write( "And so, 14x = (15x)+(-x) so that (15x)X(-x) = -15x^2 = (3x^2)X(-5)
\n" ); document.write( "=(3x^2+15x)-x-5
\n" ); document.write( "=3x(x+5)-1(x+5)
\n" ); document.write( "=3xp-p where p= (x+5)
\n" ); document.write( "=p(3x-1)
\n" ); document.write( "=(x+5)(3x-1) \r
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