Question

Jenny is working on simplifying the algebraic expression 3x+21
when x=5
. Her steps are as follows:

Step 1: 35+21
Step 2: 15+21
Step 3: 36
In which step did Jenny make a mistake? What should she have done differently?

(1 point)
Responses

Step 2, Jenny should've added 3 and 5 to get 8.
Step 2, Jenny should've added 3 and 5 to get 8.

Step 3, 15+21
should be 15⋅21
.
Step 3, 15 plus 21 should be 15 times 21.

Step 2, Jenny should've calculated the value of 35
to be 243.
Step 2, Jenny should've calculated the value of 3 to the 5th power to be 243.

Step 1, Jenny should've multiplied 3⋅5
instead of writing 5 as the exponent.
Step 1, Jenny should've multiplied 3 times 5 instead of writing 5 as the exponent.
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Question
Jenny is working on simplifying the algebraic expression 3x+21
when x=5
. Her steps are as follows:

Step 1: 35+21
Step 2: 15+21
Step 3: 36
In which step did Jenny make a mistake? What should she have done differently?

(1 point)
Responses

Step 2, Jenny should've added 3 and 5 to get 8.
Step 2, Jenny should've added 3 and 5 to get 8.

Step 3, 15+21
should be 15⋅21
.
Step 3, 15 plus 21 should be 15 times 21.

Step 2, Jenny should've calculated the value of 35
to be 243.
Step 2, Jenny should've calculated the value of 3 to the 5th power to be 243.

Step 1, Jenny should've multiplied 3⋅5
instead of writing 5 as the exponent.
Step 1, Jenny should've multiplied 3 times 5 instead of writing 5 as the exponent.
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Answer 1

Jenny made a mistake in **Step 1**. She incorrectly wrote \( 35 \) instead of calculating \( 3x \) when \( x = 5 \).

What she should have done is multiply \( 3 \) by \( 5 \) to get \( 15 \) for the expression \( 3x + 21 \).

So the correct first step should be:

Step 1: \( 3 \cdot 5 + 21 = 15 + 21 \).

Thus, the answer is:

**Step 1, Jenny should've multiplied \( 3 \cdot 5 \) instead of writing \( 5 \) as the exponent.**