3) 124 + (-52) . 124 + (-124 ) . (-47)
= 124 + (-52) . 124 + 124 . 47
= 124 \(\left[\left(-52\right)+1+47\right]\)
= 124.(-3)
= -372
4) 53. (51 + 4) + 53. ( 49+96) + 53
= 53 . 55 + 53 . 145 + 53
= 53(55+145) + 53
= 53 . 200 + 53
= 10600 +53
= 10653
1 . Tính nhanh
a/ 15 . ( 27 + 18 + 6 ) + 15 . ( 23 + 12 )
b/ 14 . 35 . 5 + 10 . 25 .7 + 20 . 70
c/ 53 . ( 51 + 4 ) + 53 . ( 49 + 96 ) + 53
d/ 46 . ( 27 + 75 ) + 8 . ( 58 + 25 ) . 2
1. Tính
a, 1+7+8+15+23+...+160
b, 17+4+5+9+19+...+60+9
c, 78*3+78*24+78*17*22*72
d, 53*39+47*39+47-53*21-47*21
e, 2*53*12+4*6*87-3*8*40
g, 5*7*77-7*60+49*25-15*42
h, 1*2+2*3+3*4+...+2016*2017
Tính nhanh:
7) ( 135 - 35) . (-47) + 53 . ( -48 - 52)
8) ( 35 - 5) . (-4) + 24 . ( -13 -17)
tính nhanh nếu có thể:
a)\(\dfrac{4}{2.4}+\dfrac{4}{4.6}+\dfrac{4}{6.8}+.....+\dfrac{4}{2008.2010}\)
b)\(\dfrac{\dfrac{3}{41}-\dfrac{12}{47}+\dfrac{27}{53}}{\dfrac{4}{41}-\dfrac{16}{47}+\dfrac{36}{53}}\)
\(\dfrac{\dfrac{3}{41}-\dfrac{12}{47}+\dfrac{27}{53}}{\dfrac{4}{41}-\dfrac{16}{47}+\dfrac{36}{53}}+\)
đề bài là \(Tính\)
Chứng tỏ: 1- 1/2 + 1/3 - 1/4 + 1/5 - 1/6 +.........+ 1/99 - 1/100 = 1/51 + 1/52 + 1/53 + .....+ 1/100
A)(3 1/3+2,5):(3 1/6-4 1/5)-11/31.
b)3/21-12/47+27/53:4/41-16/47+36/53.
dề bài:tính giá trị biểu thức.
Tính nhanh:
(25+51) + (45 - 25 - 53 - 51)
53*39 +47*39 -53*21-47*21