a)goc C= 180do-goc A- goc B= 180do-90do-50do=40do

suy ra goc C= 40do

xac suat bien co ban chon duoc nam la: 1/6

a)     A(x)= 2x3-x2+3x-5

+

       B(x)= 2x3+x2+x+5

________________________

A(x)+B(x)=4x3     +4x

b) ta co:

4x3+4x=0

4x3      =0-4x

4x3      =-4x

  x3      =(-4x):4

  x3      =-x

  x        =x

Goi x,y lan lout la so sach giao khoa hai lop quyen gop duoc la

x/5=y/6 va x+y= 121( quyen sach)

x/5=y/6=x+y/5+6=121/11=11

x=5.11=55

y=6.11=66

vay so sach giao khoa hai lop lan luot quyen gop la :

7a=55 quyen sach GK

7b=66 quyen sach GK

Đúng

a)c,e

b)ta co:

x/4=y/7=x+y/4+7=55/11=5

x=4*5= 20

y=7*5=35

Lộn 101

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