actual math qustion

Question

this is the math question

Jenny used the steps below to find the value of expression: 7x 13.

step1. 7x13=7x(8+5)

step 2. 7x8+5

step 3. 56=5=61

Part A= Explain the error that Jenny made and than correct the error.

 

Part B= Jenny said that 6x(5x4)=(6x5)x4. Explain why she decided the equation was true.

Answer 1

The mistake is in Step 2.

 

7x(8+5) is not the same as 7 x 8 + 5. The parentheses matter. The 7 needs to be distributed to BOTH the 8 AND the 5. Step 2 should read:

 

7x8 + 7x5

 

 

That means that Step 3 should then read: 

 

56 + 35 = 91

 

 

 

For Part B, Jenny was correct. You may group the items of a product however you want. This is stated by the Associative Property.