tính nhanh hay gì?

\(g,101+\left(-60\right)+29+\left(-40\right)=41+29+\left(-40\right)=70+\left(-40\right)=30\)

\(h,167+\left(-252\right)+52+\left(-67\right)=\left(-85\right)+52+\left(-67\right)=\left(-33\right)+\left(-67\right)=-100\)

\(i,38-138+250-350=\left(-100\right)+250-350=150-350=-200\)

\(k,118+107-\left(118-93\right)-50=225-25-50=100-50=50\)

\(m,40+\left(139-172+99\right)-\left(139+199-172\right)=40+\left[\left(-33\right)+99\right]-\left(338-172\right)\)

\(=40+66-166=106-166=-60\)

Phương pháp giải:

So sánh các cặp chữ số cùng hàng theo thứ tự từ trái sang phải. 

Lời giải chi tiết:

115 < 119      137 > 130

156 = 156      149 < 152

185 > 179      165 > 156

189 < 194      172 > 170

192 < 200      190 > 158

a)1720

b)900

a) 172+172×2+172×3+172×4

=172x1+172x2+172x3+172x4

=172x(1+2+3+4)

=172x10

=1720

b) 152+592-92-52-81+381

=(152-52)+(592-92)+(381-81)

=100+500+300

=900

\(\Rightarrow2\left(x-172\right)=156+111\\ \Rightarrow2\left(x-172\right)=267\\ \Rightarrow x-172=\dfrac{267}{2}\\ \Rightarrow x=\dfrac{267}{2}+172\\ \Rightarrow x=\dfrac{267+2\times172}{2}\\ \Rightarrow\dfrac{267+344}{2}=\dfrac{611}{2}\)

\(2\left(x-172\right)-111=156\)

\(\Rightarrow2\left(x-172\right)=156+111\)

\(\Rightarrow2\left(x-172\right)=267\)

\(\Rightarrow x-172=\dfrac{267}{2}\)

\(\Rightarrow x=\dfrac{267}{2}+172\)

\(\Rightarrow x=\dfrac{267}{2}+\dfrac{172\cdot2}{2}\)

\(\Rightarrow x=\dfrac{267}{2}+\dfrac{344}{2}\)

\(\Rightarrow x=\dfrac{611}{2}\)

a: 43/52>26/52=1/2=60/120

b: 17/68=1/4<1/3=35/105<35/103

c: \(\dfrac{2018\cdot2019-1}{2018\cdot2019}=1-\dfrac{1}{2018\cdot2019}\)

\(\dfrac{2019\cdot2020-1}{2019\cdot2020}=1-\dfrac{1}{2019\cdot2020}\)

2018*2019<2019*2020

=>-1/2018*2019<-1/2019*2020

=>\(\dfrac{2018\cdot2019-1}{2018\cdot2019}< \dfrac{2019\cdot2020-1}{2019\cdot2020}\)

A = 1 7 − 1 13 = 6 91 .

ta có 166/256 lớn hơn phaand tử lớn hơn ko so sánh đc phần bù

phân số 166/156 lớn hơn đó bạn

\(268-4.\left\{156-6.\left[54-2.\left(3^2+6\right)\right]\right\}.x=172\)

\(\Leftrightarrow268-4.\left\{156-6.\left[54-2.15\right]\right\}.x=172\)

\(\Leftrightarrow268-4.\left\{156-6.24\right\}.x=172\)

\(\Leftrightarrow268-4.12.x=172\)

\(\Leftrightarrow268-48x=172\)

\(\Leftrightarrow48x=96\)

\(\Leftrightarrow x=2\)

hok tốt nha!!!!

= 52 nha em