1. tìm x
2x -3 = x + 1/2
2. tính bằng hai cách
A = ( 2008 - 2/135 +1/50) - ( 1 - 7/135 +4/50) - ( 5+ 5/135 +3/50)
cần gấp nha
tính bằng cách thuận tiện nhất
( 2008 - 2/135 + 1/50) - (1 - 7/135 + 4/50) - (5 + 5/135 + 3/50)
\(=2008-\dfrac{2}{135}+\dfrac{1}{50}-1+\dfrac{7}{135}-\dfrac{4}{50}-5-\dfrac{5}{135}-\dfrac{3}{50}\)
\(=2002\)
Tính nhanh
a. B=5/6 -6/7+7/8-8/9+9/10-5/6+6/7+7/8+8/9
b. (2008-2/135+1/50) - (1-7/135+4/50) _ ( 5 + 5/135+3/50)
các bạn giúp mình nha
BT1: Tính
5) ( 2008 - \(\frac{2}{135}\) + \(\frac{1}{50}\) ) - ( 1 - \(\frac{7}{135}\) + \(\frac{4}{150}\)) - ( 5 + \(\frac{5}{135}\) + \(\frac{3}{50}\))
Ta có: \(\left(2008-\dfrac{2}{135}+\dfrac{1}{50}\right)-\left(1-\dfrac{7}{135}+\dfrac{4}{150}\right)-\left(5+\dfrac{5}{135}+\dfrac{3}{50}\right)\)
= \(2008-\dfrac{2}{135}+\dfrac{1}{50}-1+\dfrac{7}{135}-\dfrac{4}{150}-5-\dfrac{5}{135}-\dfrac{3}{50}\)
= (2008-1-5) + \(\left(\dfrac{1}{50}-\dfrac{3}{50}\right)-\left(\dfrac{2}{135}-\dfrac{7}{135}\right)-\dfrac{4}{150}\)
=2002 \(-\dfrac{1}{25}\)+\(\dfrac{1}{27}\)\(-\dfrac{4}{150}\)
=2001,9(3)
\(\left(2018-\frac{2}{135}+\frac{1}{50}\right)-\left(1-\frac{7}{135}+\frac{4}{50}\right)-\left(5+\frac{5}{135}+\frac{3}{50}\right)\)
\(\left(2018-\frac{2}{135}+\frac{1}{50}\right)-\left(1-\frac{7}{135}+\frac{4}{50}\right)-\left(5+\frac{5}{135}+\frac{3}{50}\right)\)
\(=2018-\frac{2}{135}+\frac{1}{50}-1+\frac{7}{135}-\frac{4}{50}-5-\frac{5}{135}-\frac{3}{50}\)
\(=2012-\frac{6}{50}\)
( 2018 - \(\frac{2}{135}\)+ \(\frac{1}{50}\)) - ( 1 - \(\frac{7}{135}\)+ \(\frac{4}{50}\)) - (5 + \(\frac{5}{135}\)+ \(\frac{3}{50}\))
1. Tính nhanh ( nếu có )
(-14).(-125).(-50).8
35.(72-135)-135(72-35)
2. Tìm số nguyên x
x +3-3.(x+5) = x-9
Giúp mình nhé, mình cầm gấp :v!
1. Tính nhanh ( nếu có )
(-14).(-125).(-50).8
35.(72-135)-135(72-35)
2. Tìm số nguyên x
x +3-3.(x+5) = x-9
Giúp mình nhé, mình cầm gấp :v!
a.13.(23+22)-3.(17+28)
b.-48+48.(-78)+48(-21)
c.135.(171-123)-171.(135-123)
d.1-2+3-4+..........+99-100
e.2-4+6-8+..........+48-50
j.-1+3-5+7-........-97+98-99-100
a) 13.(23+22)-3.(17+28)
= 13.45 - 3.45
= 45(13-3)
= 45.10 =450
b) -48+48.(-78)+48(-21)
= -48 + 48(-78 - 21)
= -48 + 48.(-99)
= -48 + ( -4752)
= -4800
c) 135.(171-123)-171.(135-123)
= 135.171 - 135.123 - 171.135 + 171.123
= (135.171 - 171.135) - (135.123 - 171.123)
= - 123(135 - 171) = (-123).(-36)= 4428
d: =(1-2)+(3-4)+...+(99-100)
=(-1)+(-1)+...+(-1)
=-50
j: SỬa đề: -1+3-5+7-...-97+99
=(-1+3)+(-5+7)+...+(-97+99)
=2+2+...+2
=2*50=100
e: Sửa đề: 2-4+6-8+...+46-48+50
=(2-4)+(6-8)+...+(46-48)+50
=50-2*24=50-48=2
Tính nhanh bằng 2 cách:
a) 135 - 13 - 22 + 50
b) 3 - 5 + 7 - 9 + 11 - 13 + 15
c) 4 - 6 + 8 - 10 + 12 - 14 + 16
a) 135 - 13 - 22 + 50
= 135-(13+22)-50
= 135- 35 + 50
= 100 -50
= 50