a) (44 x 52 x 60) : (11 x 13 x 15)

= (44 : 11) x ( 52 : 13) x (60 : 15)

= 4 x 4 x 4 = 64

d) 1 + 6 + 11 + 16 + ... + 46 + 51

Ta có : 1 + 6 + 11 + 16 + ... + 46 + 51 ( có 11 số )

= (51 + 1) x 11 : 2 = 286

a, Ta thấy 44:11=4               ,         52;13=4        ,                60:15=4,                                                                                                                         => 4*4*4=64             

585

(15+75)+(20+70)+(25+65)+(30+60)+(35+55)+(40+50)+45
= 90+90+90+90+90+90+45
= 90.6+45
= 540+45=585

Bài làm

\(A=\frac{0,24\cdot450+0,8\cdot15\cdot5+3\cdot3\cdot8}{65-60+55-50+45-40+35-30+25-20+5}\)

\(A=\frac{0,24\cdot45\cdot10+0,8\cdot15\cdot5+3\cdot3\cdot8}{\left(65-60\right)+\left(55-50\right)+\left(45-40\right)+\left(35-30\right)+\left(25-20\right)+5}\)

\(A=\frac{2,4\cdot45+0,8\cdot75+72}{5+5+5+5+5+5}\)

\(A=\frac{2,4\cdot45+0,8\cdot\frac{5}{3}\cdot45+1,6\cdot45}{30}\)

\(A=\frac{45\left(2,4+\frac{4}{5}\cdot\frac{5}{3}+1,6\right)}{30}\)

\(A=\frac{45\cdot\left(\frac{20}{15}+\frac{36}{15}+\frac{24}{15}\right)}{30}\)

\(A=\frac{3\cdot\frac{80}{15}}{2}\)

\(A=\frac{\frac{80}{5}}{2}\)

\(A=\frac{80}{5}\cdot\frac{1}{2}\)

\(A=\frac{40}{5}\)

\(A=8\)

\(55+60+45+30+40+70\)

\(=\left(55+45\right)+\left(60+40\right)+\left(30+70\right)\)

\(=100+100+100=300\)

\(4+20+6+80=\left(4+6\right)+\left(20+80\right)=10+100=110\)

a) \(55+60+45+30+40+70\)

\(=\left(55+45\right)+\left(60+40\right)+\left(30+70\right)\)

\(=100+100+100\)

\(=100.3=300\)

b) \(4+20+6+80\)

\(=\left(4+6\right)+\left(20+80\right)\)

\(=10+100=110\)

a)1-1+1=1

a.1

b.1,140119483

c.0,353338015

a) \(A=2sin30^o+3cos45^o-sin60^0\)

\(\Leftrightarrow A=2.\dfrac{1}{2}+3.\dfrac{\sqrt[]{2}}{2}-\dfrac{\sqrt[]{3}}{2}\)

\(\Leftrightarrow A=1+\dfrac{3\sqrt[]{2}}{2}-\dfrac{\sqrt[]{3}}{2}\)

\(\Leftrightarrow A=1+\dfrac{\sqrt[]{3}\left(\sqrt[]{6}-1\right)}{2}\)

b) \(B=3cos30^o+3sin45^o-cos45^o\)

\(\Leftrightarrow B=3\dfrac{\sqrt[]{3}}{2}+3\dfrac{\sqrt[]{2}}{2}-\dfrac{\sqrt[]{2}}{2}\)

\(\Leftrightarrow B=\dfrac{3\sqrt[]{3}}{2}+\dfrac{2\sqrt[]{2}}{2}\)

\(\Leftrightarrow B=\dfrac{3\sqrt[]{3}}{2}+\sqrt[]{2}\)

a)     5/30+15/90+25/150+35/210+45/270

       =1/6+1/6+1/6+1/6+1/6

       =1/6 x 5

       =5/6

b)     1/2+1/6+1/12+1/20+....+1/56

        =1/1x2+1/2x3+1/3x4+1/4x5+.....1/7x8

        =1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+.......-1/7+1/7-1/8

        =1/1-1/8

         =7/8

c)     mình chịu

thank you bn nhìu nha