310 nha bạn

Tk mình tk lại

678-420+52 = 258 +52 = 310

\(678-420+52\)

\(=\left(678+52\right)-420\)

\(=730-420\)

\(=310\)

k mk nha

thank you

125 x 420 = 52500

y x 62 - y x 52 = 420

y x (62 - 52) = 420

y x 10 =420

y = 420: 10

y = 42

y *  62 - y * 52 = 420

=>y*(62-52)=420

=>y*10=420

=>y=420:10

=>y=42

42 nhe 

a) 17-(5-9)+3.(-6)=17-(-4)+(-18)=17+4-18=21-18=3

b)175-(-58)+(-40)+25=175+58-40+25=(175+25)+(58-40)=200+18=218

c)  (47-17).(-3)^2-8.(-6-24)=423-153+48+192=(432-153)+(48+192)=270+240=510

d)138-420+(-52)-(-272)=138-420-52+272=(138-420)+(-52+272)=-282+220=-62

Bài làm:

\(\frac{215}{300}=\frac{43}{60}\)

\(\frac{1200}{2010}=\frac{40}{67}\)

\(\frac{105}{420}=\frac{1}{4}\)

\(\frac{125}{420}=\frac{25}{84}\)

#Học_tốt

\(\dfrac{215}{300}\) = \(\dfrac{215:5}{300:5}\) = \(\dfrac{43}{60}\)

\(\dfrac{1200}{2010}\) = \(\dfrac{1200:30}{2010:30}\) = \(\dfrac{40}{67}\)

\(\dfrac{105}{420}\)  = \(\dfrac{105:105}{420:105}\) = \(\dfrac{1}{4}\)

\(\dfrac{125}{420}\) = \(\dfrac{125:5}{420:5}\) = \(\dfrac{25}{84}\)

\(2\sqrt{5}-3\sqrt{125}+\sqrt{52}-2\sqrt{8}\)

\(=2\sqrt{5}-15\sqrt{5}+2\sqrt{13}-4\sqrt{2}\)

\(=-13\sqrt{5}+2\sqrt{13}-4\sqrt{2}\)