Question

Select the correct answer.

What is the product of (x - 3) and (x + 7)?

`{x}^(2) + 10x - 21`

`{x}^(2) + 4x - 21`

`{x}^(2) - 4x - 21`

`{x}^(2) - 10x - 21`
​

Answer 1

⚘ Solution:

Expanding parentheses,

➝ (x - 3)(x + 7)

➝ x(x + 7) - 3(x + 7)

➝ x² + 7x - 3x - 21

➝ x² + 4x - 21

Option B

Explore more:-

Expanding brackets involves removing the brackets by multiplying each term in the brackets by every term outside of the brackets. The process of expansion is also known as the distributive law. When expanding brackets be very careful of negative numbers.

Once a set of brackets has been expanded, it is possible for several like terms to appear.

When this is the case you can use the box method or FOIL to ensure you expand the set of brackets properly. In general:

`\large{ \boxed{ \rm{(a + b)(c + d) = ac + ad + bc + bd}}}`

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