Question

Multiply 73 x 67 using the form (a+b)(a-b)

Answer 1

4891

Explanation:

73 can be written as (70 + 3), and 67 can be written as (70 - 3) which means that 73 × 67 is the same as (70 + 3)(70 - 3)

The next step is to use FOIL and expand the brackets:

• First: 70 × 70 = 4900
• Outside: 70 × -3 = -210
• Inside: 3 × 70 = 210
• Last: 3 × -3 = -9

(70 + 3)(70 - 3) = 4900 + -210 + 210 + -9

This can be simplified to 4891.

Hope this helps!