Step by step
The question
Question: find the value of (a − b)² when a = 3 and b = 7.
(a − b)2
a = 3, b = 7
1 Put the numbers in
We put 3 in place of a and 7 in place of b.
= (3 − 7)2
2 Brackets first
Brackets come first.
Order: ( ) → x² √ → × ÷ → + −
We take away more than we have.
Start at 3.
Go down 7.
We pass 0 and land on −4.
= (−4)2
3 Powers
(−4)² means −4 times −4.
Minus times minus is plus.
(−4)2 = (−4) × (−4) = 16
That is 16.
= 16
So (a − b)² is 16 when a = 3 and b = 7.
Let's look back.
First: put the numbers in.
Then: brackets first.
Last: powers.
Answer
= 16