Question

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

18–3[21–(9–5)2]+8
=
18–3[21–42]+8 Step 1
=
18–3[21–16]+8 Step 2
=
18–35+8 Step 3
=
155+8 Step 4
=
75+8 Step 5
=
83 Step 6
Is Kimi's work correct?

Answer 1

Kimi made several mistakes in evaluating the expression. The correct steps show that the final result of the expression 18−3[21−(9−5)2]+8 should be 11, not 83.

Step-by-step explanation:

Kimi's attempt to evaluate the expression 18−3[21−(9−5)2]+8 contains some errors. Let's go through the correct steps:

1. Simplify inside the parentheses: (9−5) which is 4.
2. Square the result: 42 which is 16.
3. Substitute into the original expression: 18 − 3[21 − 16] + 8.
4. Simplify inside the brackets: 21 − 16 which is 5.
5. Multiply by 3: 3 × 5 which is 15.
6. Subtract from 18: 18 − 15 which is 3.
7. Finally, add 8: 3 + 8 which is 11.

Therefore, the correct result should be 11, not 83.