Question

Tính nhanh:
a) 1001^2
b) 29,9 . 30,1
c) 199^2
d) 84^2 - 16^2
e) 313^2 - 312^2
f) 47 . 53 
Giúp mik vs! mik cần gấp lắmmm !!!
Mik cám ơn 

Answer 1

`a)1001^2`

`=(1000+1)^2=1000000+2000+1`

`=1002001`

`b)29,9.30,1`

`=(30-0,1)(30+0,1)`

`=30^2-0,1^2`

`=900-0,01=899,99`

`c)199^2=(200-1)^2`

`=40000-400+1`

`=39601`

`d)84^2-16^2`

`=(84-16)(84+16)`

`=100.68`

`=6800`

`e)313^2-312^2`

`=(313-312)(313+312)`

`=625`

`f)47.53`

`=(50-3)(50+3)`

`=2500-9=2491`