Question

Which must be present in order for factoring by grouping to apply? - The ratios of the first two terms and the second two terms must be positive. - The ratio of the first two terms must be equivalent to the ratio of the last two terms. - There must be at least three terms. - The first and the last terms must be perfect squares.

Answer 1

The ratio of the first two terms must be equivalent to the ratio of the last two terms

Answer 2

For factoring by grouping to apply, the ratio of the first two terms must be equal to the ratio of the last two terms

Explanation:

Here, we want to select which of the options must be present in order for factoring by grouping to apply.

The correct answer is that the ratio of the first two terms must be equivalent to the ratio of the last two terms

What this mean is that we must have an equal ratio two times

This practically plays out each time we are to factorize quadratic expressions

For example, in the case of

x^2 -12x + 20

This can be written as;

x^2 - 10x - 2x + 20

which can then be written as x(x-10) -2(x -10)

= (x-2)(x-10)

The first two terms have a ratio of ;

x^2/-10x while the last two terms have a ratio -2x/20

Thus, we have -x/10 and -x/10

We can see here that the ratios of both sets are equivalent