Question

Factorise the following:

120 – 30х²

Answer 1

Given: 120 – 30х²

Step-wise calculation:

1. Take out the common factor from both terms, which is 30:

120 – 30x² = 30(4 – x²)

2. Recognize the expression inside the bracket as a difference of squares:

4 – x² = (2)² – (x)²

3. Apply the difference of squares factorization formula a² – b² = (a + b)(a – b):

4 – x² = (2 + x)(2 – x)

4. Substitute back:

120 – 30x² = 30(2 + x)(2 – x)