Sum and Difference of Two cubes

In 2013 alevel, factorisation of the difference of two cubes can be used in one of the questions

Here are the formulas students should remember:

sum and difference of two cubes

Students can use the mnemonic “SOAP” to help them remember the formula.

S: Same sign

O: Opposite sign

A: Always

P: Positive

Juggling: shortcut to long division

Juggling is a shortcut to long division, especially in the case where the degree of the numerator is the same as the denominator. In H2 math, juggling is a useful technique in finding the asymptote of graphs and integration.

juggling

Try this long division problem!

Many students, including JC H2 math students, have difficulty doing long division when it comes to complex problems.

Try this problem to test or sharpen your long division skills.

Question

If Tex2Img_1403575339 is a factor of Tex2Img_1403575464, prove by long division that Tex2Img_1403575555

Solution

long division

Synthetic division

Synthetic division can be used to divide a polynomial by a linear divisor, which is commonly required in H2 math and Amath.

It is faster than the traditional long division.

How to do Synthetic division

Partial fraction: Cover-up rule

Partial fraction is commonly used in binomial expansion, method of difference and integration.

When the divisor consists only of linear factors, cover up rule can be used to find the constants in the partial fraction quickly.

Example

Express Tex2Img_1400545440 in partial fraction.

Tex2Img_1400545549

By cover up rule,

1

Therefore

Tex2Img_1400546214

2

0 = A+C

3

Therefore,

fraction final