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to solve quadratic equations the first thing is to look for factor pairs of the constant term, in this case that is +20.
\n" ); document.write( "factors of +20 are: (remember either these have to be both positive or both negative numbers because negative multiplied by negative gives a positive answer)
\n" ); document.write( "plus/minus 1 and 20:
\n" ); document.write( "plus/minus 2 and 10:
\n" ); document.write( "Plus/minus 4 and 5.
\n" ); document.write( "Now we look to see if any of those factor pairs can be added to make the coefficient of the x term (that's the number in front of the x) which is +9.
\n" ); document.write( "Obviously the factor pair we need are plus 4 and 5 because 4 + 5 = 9
\n" ); document.write( "Now we get two brackets and put an x in both and one of the factors in each bracket
\n" ); document.write( "Like this
\n" ); document.write( "(x+4)(x+5)
\n" ); document.write( "making this equal zero means that either one of these brackets could equal zero, that is,
\n" ); document.write( "either (x+4)=0 or (x+5)=0
\n" ); document.write( "If (x+4)=0 then x = -4
\n" ); document.write( "OR
\n" ); document.write( "If (x+5)=0 then x = -5
\n" ); document.write( "These are the two solutions
\n" ); document.write( "x = -4 or -5 \n" ); document.write( "