bài 1: tính nhanh:
\(\frac{18.123+9.436.2+3.5310+6}{1+4+7+...+100-410}\)
tính nhanh (18.123+9.436.2+3.5310.6):(1+4+7+.......+100-410)
tính nhanh: ( 18.123+9.436.2+3.5310.6):(1+4+7+.....+100-410)
2.Tính nhanh :
A= (18.123+9.436.2+2.5310.6) : (1+4+7+....+100-410)
Tính nhanh: (18.123+9.436.2+3.5310.6) : ( 1+4+7+...+100-410 )
Ta có:
+) \(1+4+7+...+100=\left(1+100\right)+\left(4+97\right)+...+\left(49+52\right)\)(34 cặp)
\(=101.34=3434\)
+) \(3434-410=3024\)
+) \(\left(18.123+9.436.2+3.5310.6\right)=18\left(123+436+5310\right)\)
\(=18.5869=105642\)
Vậy \(A=105642:3024\approx34,93\)
Tính nhanh: (18.123 + 9.436.2 + 3.5310.6 ) : ( 1 + 4 + 7 + ....... + 100 - 410 )
Tính nhanh (18.123 + 9.436.2 + 3.5310.6) : (1 + 4 + 7 + ... + 100 - 410)
Tính nhanh
(18.123+9.436.2+3.5310.6):(1+4+7+...+100-410)
(18.123+9.436.2+3.5310.6)/(1+4+7+.....+100-410)
Tính nhanh : \(\left(18.123+9.436.2+3.5310.6\right):\left(1+4+7+|11|+100-410\right)\)
b, Ta có:
+) 1 + 4 +7 +……+ 100 = ( 1+100) + ( 4 + 97) +…….+ ( 49+ 52) = 101 . 34 = 1434
34 cặp
+) 1434 – 410 = 1024
+) ( 18 . 123 + 9 . 436 . 2 + 3 . 5310. 6 ) = 18 . ( 123 + 436 + 5310 )
= 18 . 5869 = 105642 ; Vậy A = 105642 : 1024 103,17