1、
(-2a？ bc)？ ×(-ab？ )
=[(-2)? a^(3×2)b？ c？ ]×(-ab？ )
=(4a^6b？ c？ )×(-ab？ )
=-4a^7b？ c？
2、
Simplify first, then evaluate:
2 (x+5) (x-4)-3 (x-6) (x+ 1), where x = 2.
Solution:
Original formula = 2 (x? +x-20)-3(x？ -5x-6)
=2x？ +2x-40-3x？ + 15x+ 18
=-x？ + 17x-22
=-2? + 17×2-22
=-4+34-22
=8
Dig a square with a side length of 6.75cm in the middle of the square with a side length of 13.25cm, and find the area of the rest.
Solution:
What about the rest?
= s big square -s small square
= 13.25? -6.75?
= 175.5625-45.5625
= 130cm？
∴ The area of the remaining part is 130cm?