Which of the following would best be solved using factoring by grouping?
1) x^2+3x- 10=0
2)3x^2+12x=8
3)x^2=25
4)x^3+ 5x^2- 9x- 45=0

ANSWER

4)x^3+ 5x^2- 9x- 45=0

EXPLANATION

Factoring by grouping is used to factor expressions that have four terms.

Among the given options, the fourth option is

There are already four terms in this expression.

So we group the first two and the last two and factor.

We can see that x² is common to the first two terms and -5 is common to the last 2 terms.

The fourth choice is correct.

see explanation

step-by-step explanation:

since the sequence is geometric there is a common ratio r between consecutive terms, that is

r = 4 ÷ - 2 = - 2

r = - 8 ÷ 4 = - 2

r = 16 ÷ 8 = - 2

the next term - 13 must be incorrect as it should be - 32 for the sequence to be geometric.

the first 4 terms are therefore geometric with common ratio r = - 2