alternative ways to do partial fraction?
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what are alternative ways to do partial fraction?
other than the normal method of mulplying the whole term over and comparing coefficient which is super headache method
i heard of "cover-up method", very quick can get answer liao
and also something like
5 / (x+1)(x-2) = A / (x+1) + B / (x-2)
A = (x + 1) * 5 / (x+1)(x-2) | replace all x by -1
maths experts please teach -
burn your question paper............problem solved.
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Cover-up rule:
[(4-3x)/(x+2)(1-2x)]=[A/(x+2)]+[B/(1-2x)]
A=[(4-3x)/(1-2x)]putx=-2
B=[(4-3x)/(x+2)]putx=1/2
If memory serves me right, I think that not all partial fractions can use the cover-up rule. -
Ouuuhh... i knoe partial fraction!! i know i know!!
but forgotten le..
paiseh...
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you born in 1988 already studied partial fractions?Originally posted by polarsnake:Cover-up rule:
[(4-3x)/(x+2)(1-2x)]=[A/(x+2)]+[B/(1-2x)]
A=[(4-3x)/(1-2x)]putx=-2
B=[(4-3x)/(x+2)]putx=1/2
If memory serves me right, I think that not all partial fractions can use the cover-up rule. -
firstly to solve partial fractions, must get proper fractions (where by the power of x in the numerator is LESS than the power of x in the denominator). If it is improper then do long divison first.
otherwise cover up here multiply there also no use since you'll get the wrong answer anyway. -
always use cover up first if the denominator is a linear function. if its quadratic, expand it out and compare coefficients to get the values of the constants. dont think u shud to bother about alternative becos usually questions of partial fractions carry less than 5 marks in maths paper 1.
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Partial fractions...usu used if the power in the denominator is in terms like: (x+1)(x-1), i.e. powers of 1. Cannot be used for higher powers of x.
And, like wad the above ppl have said. Numerator power is smaller than denominator, otherwise factorise first.