Question

Justine tried to evaluate an expression. Here is her work:

10 - 4 + 2(4)² = 10 - 4 + 82 = 10 - 4 + 64 = 6 + 64 = 70. Is Justine's work correct? Explain her mistake.

Answer 1

Justine's work was incorrect due to a mistake in order of operations. The correct answer is 38, attained by first calculating the exponent, then multiplication, followed by subtraction and addition.

Step-by-step explanation:

Justine made a mistake in evaluating the expression 10 - 4 + 2(4)². The correct steps to evaluate the expression are:

1. Calculate the exponent (4)², which is 4 x 4 = 16.
2. Multiply 16 by 2 to get 32.
3. Combine the products and the remaining numbers in the expression: 10 - 4 + 32.
4. Subtract and add in order from left to right: 6 + 32 = 38.

The correct answer is 38, not 70. It's important to follow the order of operations, known as PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction), to evaluate expressions correctly.