Option 1 : -22
using formula
(a + b )(a - b ) = a^2 - b^2
(√10 + 2√8) (√10 - 2√8)
= (√10)^2 - (2√8)^2
= 10 - 2×2×8=10-32
= -22
2nd question answer is option 3
Answer: answer is C because if you do 2x9 abd 2x3 you 18c-6d and you cant subtract thise cause they have different variables
Step-by-step explanation:
The system of equations:2 y = - x - 12 y = x + 5---------------------- x - 1 = x + 5- 2 x = 5 + 1- 2 x = 6x = - 6 : 2x = - 32 y = - 3 + 52 y = 2y = 1The solution is ( - 3 , 1 ).Answer: The x-coordinate of the solution to the system is: x = - 3.
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Answer:
The correct option is (d)-He wrote commutative instead of associative in Step 2.
Step-by-step explanation:
Commutative property: 
Associative property:
Now consider the provided expression.
(6.2 − 1.6) − 4.4 + 7.8
Step 1
(6.2 − 1.6) − 4.4 + 7.8
Step 2 Use Associative property
6.2 + (−1.6 − 4.4) + 7.8
Step 3: Simplify
6.2 − 6 + 7.8
Step 4: Use commutative property
14 − 6
Step 5: Simplify
14 − 6 = 8
Hence, the wrong step is step 2. He wrote commutative instead of associative in Step 2.
Therefore, the correct option is (d)-He wrote commutative instead of associative in Step 2.