Question

What is the value of the expression 3b - a 2 when a = 3 and b = 4?

Answer 1

Answer: 3

Explanation:

Our task is to find the value of
`\sf{3b-a^2}` when a = 3 and b = 4.

Replace each variable with its value. You should get this:

`\sf{3\cdot4-3^2}`

This is where many students can make mistakes. We need to follow the order of operations listed in PEMDAS:

Parentheses, exponents, multiplication, division, addition, and subtraction

We don't have parentheses here, so we move on to exponents, which we do have. We have 3 squared, which is 9.

So, we now have:

`\sf{3\cdot4-9}`

The operation that comes next is multiplication. We multiply 3 by 4, which gives us 12.

`\sf{12-9}`

We now have to subtract to get our final answer:

`\sf{12-9=3}`

The expression's value is 3.

Answer 2

3

Explanation:

3b - a²

substitute a = 3 and b = 4 into the expression

= 3(4) - 3²

= 12 - 9

= 3