Bài làm :

Ta có :

45.48-90.24+145

=45.48-45.48+145

=0+145

=145

bằng 1225

mong bạn tích cho mk

\(45\cdot48-90\cdot24+145\) 

\(=45\cdot2\cdot24-90\cdot24+145\)  

\(=90\cdot24-90\cdot24+145\) 

\(=0+145\) 

\(=145\)

=491.267+491.53-491.153+491.67

=491.(267+153)-491.(53+67)

=491.420-491.120

=491.(420-120)

=491.300

=147300

45.48-90.24+145

=(45.2).(48:2)-90.24+145

=90.24-90.24+145

=0+145

=145

754.75-2262.25+4568

=754.75-(2262:3).(25.3)+4568

=754.75-754.75+4568

=0+4568

=4568

23.157+15.46-23.87

=23.(147-87)+15.46

=23.60+15.46

=23.60+(15.2).(46:2)

=23.60+50.23

=23.(60+50)

=23.110

=2530

a) 93.85+17.45-170=8500

b) 491.(267+53) -491. (153+67) =49100

c) 45.48-90.24+145=145

d) 754.75-2262.25+4568=4568

e) 23.157+15.46 -23.87=2300

\(132.9+132=132.\left(9+1\right)=132.10=1320.\)

\(48.17+48.3=48.\left(17+3\right)=48.20=960\)

\(45.48-90.24+145=45.48-45.2.24+145=45.\left(48-2.24\right)+145\)=45.0+145=145

132 . 9 + 132 = 132 . 9 + 132 . 1 = 132 . (9 + 1) = 132 . 10 = 1320

48 . 17 + 48 . 3 = 48 . (17 + 3) = 48 . 20 = 960

45 . 48 - 90 . 24 + 145 = 45 . 48 - 45 . 2 . 24 + 145 = 45 . (48 - 2 . 24) + 145 = 45 . (48 - 48) + 145 = 45 . 0 + 145 = 0 + 145 = 145

754 . 75 - 2262 . 25 + 4560 = 754 . 75 - 754 . 3 . 25 + 4560 = 754 . (75 - 3 . 25) + 4560 = 754 . (75 - 75) + 4560 = 754 . 0 + 4560 = 4560

1050 : 15 - 350 : 5 + 176 = 70 - 70 + 176 = 0 + 176 = 176

132.9+132=132.(9+1)=132.10=1320

48.17+48.3=48.(17+3)=48.20=960

754.75-2262.25+4560=754.25.3-2262.25+4560=25.(2262-2262)+4560=0+4560=4560

1050:15-350:5+176= 35.30:15-35.10:5+176=35.(30:15-10:5)+176=35.(2-2)+176=0+176=176

không trả lời linh tinh

= a) 93.85+17.45-170 

Áp dụng các tính chất 

hkhlfhk'dfgdhfhgfhfd

\(\dfrac{-18}{24}+\dfrac{15}{21}=\dfrac{\left(-18\right)\times7}{24\times7}+\dfrac{15\times8}{21\times8}=\dfrac{-126}{168}+\dfrac{120}{168}=-\dfrac{1}{28}\)

Xét ΔMNP có MJ là đường trung tuyến và G là trọng tâm

nên M,G,J thẳng hàng và \(MG=\dfrac{2}{3}MJ\)

Xét ΔMNP có MJ là đường trung tuyến

nên \(\overrightarrow{MJ}=\dfrac{1}{2}\left(\overrightarrow{MN}+\overrightarrow{MP}\right)\)

=>\(\overrightarrow{MG}=\dfrac{2}{3}\cdot\dfrac{1}{2}\left(\overrightarrow{MN}+\overrightarrow{MP}\right)=\dfrac{1}{3}\overrightarrow{MN}+\dfrac{1}{3}\overrightarrow{MP}\)

=>Chọn C