a: Xét hình thang ABCD có MN//AB//CD

nên AM/AD=BN/BC

b: MA/AD+NC/BC

=BN/BC+NC/BC

=1

a)

\(\sqrt{9+4\sqrt{5}}\cdot\sqrt{6-2\sqrt{5}}\\ =\sqrt{4+4\sqrt{5}+5}\cdot\sqrt{1-2\sqrt{5}+5}\\ =\sqrt{\left(2+\sqrt{5}\right)^2}\cdot\sqrt{\left(1-\sqrt{5}\right)^2}\\ =\left(2+\sqrt{5}\right)\left(1-\sqrt{5}\right)\)

b)

\(\sqrt{3+2\sqrt{2}}-\sqrt{6-4\sqrt{2}}\\ =\sqrt{2+2\sqrt{2}+1}-\sqrt{4-4\sqrt{2}+2}\\ =\sqrt{\left(\sqrt{2}+1\right)^2}-\sqrt{\left(2-\sqrt{2}\right)^2}\\ =\sqrt{2}+1-2+\sqrt{2}=2\sqrt{2}-1\)

a: =>31-x-39=-58

=>-8-x=-58

=>x+8=58

hay x=50

b: =>-129-35+x=55

=>x-164=55

hay x=219

c: =>|x-7|=-37+127=90

=>x-7=90 hoặc x-7=-90

=>x=97 hoặc x=-83

d: =>|x-14|<2

=>x-14>-2 và x-14<2

=>12<x<16

e: =>315-x-315=43-12

=>-x=31

hay x=-31

f: =>|x-4|=4

=>x-4=4 hoặc x-4=-4

=>x=8 hoặc x=0

a: =>25-25+x=12+42-65

=>x=-11

b: =>|x+3|=4

=>x+3=4 hoặc x+3=-4

=>x=1 hoặc x=-7

c: =>x+17=13

hay x=-4

d: =>x+25-x=13-x

=>13-x=25

hay x=-12

e: =>15-30-x=x-(27-8)

=>-15-x=x-19

=>-x-x=-19+15

=>-2x=-4

hay x=2

f: \(\Leftrightarrow\left(12x-64\right)=4\cdot8=32\)

=>12x=96

hay x=8

\(g,\left[119-\left(3^3-10\right)\right].x=2448\\ \Leftrightarrow\left[119-\left(27-10\right)\right].x=2448\\ \Leftrightarrow\left[119-27+10\right].x=2448\\ \Leftrightarrow102.x=2448\\ \Leftrightarrow x=\dfrac{2448}{102}=24\\ h,\left[\left(10-x\right).2+51\right]:3-2=3\\ \Leftrightarrow\left[\left(10-x\right).2+51\right]:3=3+2=5\\ \Leftrightarrow\left[\left(10-x\right).2+51\right]=5.3=15\\ \Leftrightarrow\left(10-x\right).2=15-51=-36\\ \Leftrightarrow10-x=\dfrac{-36}{2}=-18\\ \Leftrightarrow x=10-\left(-18\right)=28\\ i,\left(x-12\right)-15=20-\left(17+x\right)\\ \Leftrightarrow x-12-15=20-17-x\\ \Leftrightarrow x+x=20-17+12+15\\ \Leftrightarrow2x=30\\ \Leftrightarrow x=\dfrac{30}{2}=15\)

\(k,-12-\left|13-x\right|=-21\\ \Leftrightarrow\left|13-x\right|=-12-\left(-21\right)=-12+21=9\\ \Leftrightarrow\left[{}\begin{matrix}13-x=9\\13-x=-9\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=13-9=4\\x=13-\left(-9\right)=13+9=22\end{matrix}\right.\)

Banj tham khaỏ

Câu này mình làm r

https://olm.vn/hoi-dap/detail/4645291454370.html

e: =(2004-2004)+(54-54)+(-15)=-15

f: =(-45789x2)-(357-57)=-91578-300=-91878

g: =(1259+1259)-(1409-1409)-12=2506

h: =(2750x2)-1229+438+29+438

=5500-1200+876

=5176

i: =-5+(-37+37)+(151+151)-45

=-50+302

=252

k: =(53-53)+(-145+145)-(359+259)=-618

e)2004-15+54-2004-54=(2004-2004)+(54-54)-15=-15

f)-45789-357-45789+57=(-45789-45789)-(357-57)=-91578-300=-91878

g)1259-1409-12+1259+140=(1259+1259)+(-1409+1409)-12=2518-12=2506

h)2750-1229+2750-(-438-29-438)=(2750+2750)-1229+438+29+438=5500-(1229-29)+(438+438)=5500-1200+876=5176

i)-5+-37-45+151--37=-5-37-45+151+37=(-5-45)+(-37+37)+151=-50+151=101

k)53-145-359-53+145-259=(53-53)+(-145+145)+(-359-259)=-618

l)-81-132-547+181-132-53=(-81+181)-(547+53)-(132+132)=100-600-264=-764

m)50-2016+50-118+2016-18=(50+50)+(-2016+2016)-(118+18)=100-136=-36