a: \(=-57\cdot75+57\cdot36-75\cdot36+75\cdot57\)
\(=36\left(57-75\right)=-18\cdot36=-648\)
b: \(=19+19\cdot42+19\cdot10\)
\(=19\cdot62=1178\)
BT2: Tính nhanh
7)\(\dfrac{-19}{34}\left(\dfrac{17}{19}+\dfrac{49}{18}\right)+\dfrac{49}{18}\left(\dfrac{19}{34}-\dfrac{18}{7}\right)\)
8)\(\dfrac{29}{32}\left(\dfrac{41}{36}-\dfrac{32}{58}\right)-\dfrac{41}{36}\left(\dfrac{29}{32}+\dfrac{18}{41}\right)\)
Tính nhanh
a, −57(75−36)−75(36−57)
b, 19−42(−19)+38.5
Tìm x
a,7x(x-10)=0
b, (4-x) . ( 2x+6)=0
c, -12(x-5) + 7 . ( 3-x ) =5
Tính nhanh
a, −57(75−36)−75(36−57)−57(75−36)−75(36−57)
b, 19−42(−19)+38.5
Tìm x
a,7x(x-10)=0
b, (4-x) . ( 2x+6)=0
c, -12(x-5) + 7 . ( 3-x ) =5
Bài 1; Tính nhanh
a) \(\left(-356+57\right)-\left(27-356\right)\)
b) \(125.\left(-24+24.225\right)\)
c) 26. ( - 125) - 125 . (-36)
Bài 2:Tìm x \(\in\) Z, biết :
a) ( 2x - 4)2 = 0 ( 2 in đậm là mũ 2
b) ( x + 5) \(⋮\) ( x + 3 )
BT2: Tính nhanh:
9)\(\dfrac{47}{51}\left(\dfrac{17}{94}-\dfrac{53}{91}\right)-\dfrac{53}{91}\left(\dfrac{91}{53}-\dfrac{47}{51}\right)\)
10)\(\dfrac{13}{19}\left(\dfrac{19}{26}-\dfrac{71}{43}\right)+\dfrac{71}{43}\left(\dfrac{13}{19}-\dfrac{86}{71}\right)\)
I= \(10101.\left(\dfrac{5}{111111}+\dfrac{5}{222222}-\dfrac{4}{3.7.11.13.37}\right)\)
B=\(71\dfrac{38}{45}-\left(43\dfrac{8}{45}-1\dfrac{17}{57}\right)\)
D= \(\left(19\dfrac{5}{8}:\dfrac{7}{12}-13\dfrac{1}{4}:\dfrac{7}{12}\right).\dfrac{4}{5}\)
F= \(\left(9.75.21\dfrac{3}{7}+\dfrac{39}{4}.18\dfrac{4}{7}\right).\dfrac{15}{78}\)
Giups mk vs!!!!!!!!
\(\left(\dfrac{1}{16}-1\right)\left(\dfrac{1}{25}-1\right)\left(\dfrac{1}{36}-1\right)...\left(\dfrac{1}{10000}-1\right)\)
BT2: Tính nhanh:
5) \(\dfrac{15}{7}\left(\dfrac{1}{5}-\dfrac{46}{45}\right)+\dfrac{46}{45}\left(\dfrac{15}{7}-\dfrac{45}{46}\right)\)
6) \(\dfrac{43}{47}\left(\dfrac{18}{37}+\dfrac{47}{43}\right)-\dfrac{18}{37}\left(\dfrac{43}{47}+\dfrac{37}{36}\right)\)
Tính
A=\(\left(\dfrac{1}{3}-1\right)\left(\dfrac{1}{6}-1\right)\left(\dfrac{1}{10}-1\right)\left(\dfrac{1}{15}-1\right)\left(\dfrac{1}{21}-1\right)\left(\dfrac{1}{28}-1\right)\left(\dfrac{1}{36}-1\right)\)
B=\(\left(1-\dfrac{1}{2^2}\right)\left(1-\dfrac{1}{3^2}\right)........\left(1-\dfrac{1}{10^2}\right)\)
C=\(1+\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+..........+\dfrac{1}{2^{2016}}\)
Giúp mk nha!Cảm ơn rất nhìu!
