a=0,lal=0: a-0,lal = a; a≤0。 lal-a; lal- 1b 1 . a & lt; 0.b<0, and then
2. additive commutative law: A+B = B+A.
3. Additive associative law: (a+b)+c=a+(b+c)
4. subtraction rule: a-b=a+(-b)
5. Multiplicative commutative law: ab=ba
6. Good law: (ab)c=a(bc)
7. Division rule: a-b=a( 1-b) (b*0)
8. The circumference of a rectangle = (length +g× 2c = (a+b) x2.
9. The circumference of a square = side length ×4C=4a.
10. Rectangular area = length and width S=ab
1 1. square area = side length x side length s = a.a = a.
12. area of triangle = base x height =2 S=ahi2.
13. area of parallelogram = bottom x height S=ah.
14. Trapezoidal area = (upper bottom+lower bottom) x height =2 5=(a+b)h-2.
15. diameter = radius× 2d = 2r radius-diameter; 2r= d:2
16. The perimeter of the garden =πx diameter =πx radius x2 C=Td =2TT.
The above is the first mathematical formula compiled by Bian Xiao. I hope it will help you.