BAI 2 CHUNG TO
1, (a -b +c) - (a+c ) =-b
2, (a + b ) -( b-a0 + c =2a+c
3, -(a+b -c) + (a-b-c )=-2b
4,a nhan ( b+ c) -a nhan (b+d) =a (c-d)
5,a nhan (b -c) =a (d +c )= a nhan ( b +d)
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(a-b+c-d)-9a+b+c+d)=a-b+c-d-a-b-c-d
=(a-a)-(b+b)+(c-c)-(d-d)
=0-2b+0-2d
=-2b-2d
(-a+b-c)+(a-b)-(a-b+c)
=-a+b-c+a-b-a+b-c
=(-a+a-a)+(b-b+b)-(c+c)
=-a+b-2c
-(a-b-c)+(b-c+d)-(a+b+d)
=-a+b+c+c-c+d-a-b-d
=(-a-a)+(b-b)+(c+c-c)+(d-d)
=-2a+0+c+0
=-2a+c
x+x+x+82=-2-x
3x+82=-2-x
3x+x=-2-82
4x=-84
x=-84:4=-21
5.(-40).x=-100
-200.x=-100
x=-100:(-200)
x=0,5
-1.(-3).(-6).x=36
-18.x=36
x=36:(-18)
x=-2
|1-4x|=7
Xảy ra hai trường hợp:1-4x=7=>4x=1-7=-6=>x=-6:4=-1,5
1-4x=-7=>4x=1+7=8=>x=8:4=2
Vì x là số nguyên nên ta chỉ có một đáp án đó là:2
x.(x-2)=0+> x=0 hoặc x=2
x.(x-2)>0=>x=-1;-2;-3;-4;...
Ta có :
abcde x 9 =edcba
Suy ra a=1 vì a>1 thì được kết quả gồm 6 chữ số.
a=1 mà e.9=..a suy ra e=9
b.9=d suy ra b=o
Hoặc b=1 và không có dư từ phép nhân trước.
Nếu b=0 ta có 10cd9 x9=9dc01
d9 x 9=c01 suy ra d=8
10c89 x 9=98c01
0c89 x 9 =8c01 suy ra c =9
Vậy số cần tìm là 10989
nhé !
\(ab+ac=a\left(b+c\right)\)
\(ab-ac+a=a\left(b-c+1\right)\)
\(ax-bx-cx+dx=x\left(a-b-c-d\right)\)
\(a\left(b+c\right)-d\left(b+c\right)=0\Leftrightarrow\left(b+c\right)\left(a-d\right)\)
\(ac-ad+bc-bd=a\left(c-d\right)+b\left(c-d\right)=\left(a+b\right)\left(c-d\right)\)
\(ax+by+bx+ay=\left(ax+ay\right)+\left(bx+by\right)=a\left(x+y\right)+b\left(x+y\right)=\left(a+b\right)\left(x+y\right)\)
ab + ac = a( b + c )
ab - ac + a = a( b - c +1 )
ax - bx - cx + dx = x( a - b - c - d )
a( b + c ) - d( b + c ) = 0 <=> ( b + c ) ( a - d )
ac - ad + bc - bd = a( c - d ) + b( c - d ) = ( a + b ) ( c - d )
ax + by + bx + ay = ( ax + ay ) + ( bx + by ) = a( x + y ) + b( x + y ) = ( a + b ) ( x + y )
Choose the best answer A, B, C or D.
1. The Temple of Literature ………………… by thousands of people every year.
A. is visit B. is visited C. was visited D. were visited
2. Emperor Ly Nhan Tong is the person who constructed …………………
A. The Imperial Academy B. Great Wall
C. One-pillar Pagoda D. Ha Long Bay
3. Doctors’ stone tablets were made of …………………
A. sand B. brick C. stone D. cement
4. The Temple of Literature is one of the historic and ………… sites in Viet Nam.
A. cultural B. culture C. old D. new
5. It’s a great idea to take some medicines ………………… you have a fever now.
A. so B. because C. but D. and
6. There is a pond ………………… the garden and the house.
A. in B. among C. between D. on
7. You’d better ………………… an umbrella because it is going to rain.
A. to take B. taking C. take D. took
8. ThienQuang well was ………………… as a world heritage.
A. met B. recognized C. seen D. watched
9. The Imperial Academy was regarded ………… the first university in Viet Nam.
A. to B. for C. as D. with
10. The Imperial Academy was ………… in 1076 under Emperor Ly Nhan Tong.
A. construct B. construction C. constructing D. constructed
11. Stone tablets were erected on the ………………… of the tortoise after each Royal examination.
A. back B. stomach C. head D. arm
12. The ………………… of this pagoda lasted 2 years.
A. instruct B. instruction C. instructing D. instructed.
a) 12,5 * 40,7 + 59,3 * 12,5
= ( 40,7 + 59,3 ) * 12,5
= 100 * 12,5
= 1250
b) 38,6 * 0,05 - 38,6 - 0,04
= 38,6 * ( 0,05 - 0,04 )
= 38,6 * 0,01
= 0,386
c) 12 : 1,25 : 0,08
= 12 : ( 1,25 * 0,08 )
= 12 : 0,1
= 120
d) ( 82,6 * 4,5 ) : 41,3
= 41,3 * ( 2 * 4,5 ) : 41,3
= 41,3 * 9 : 41,3
= 41,3 : 41,3 * 9
= 9
\(\left(a-b+c\right)-\left(a+c\right)\)
\(=a-b+c-a-c\)
\(=\left(a-a\right)+\left(c-c\right)-b\)
\(=0+0-b\)
\(=0-b\)
\(=-b\)
1) (a - b + c) - (a + c)
= a - b + c - a - c
= (a - a) - b + (c - c)
= 0 - b + 0 = -b
2) (a + b) - (b - a) + c
= a + b - b + a + c
= (a + a) + (b - b) + c
= 2a + 0 + c = 2a + c
3) -(a + b - c) + (a - b - c)
= -a - b + c + a - b - c
= (-a + a) - (b + b) + (c - c)
= 0 - 2b + 0 = -2b
4) a(b + c) - a(b + d)
= ab + ac - ab - ad
= (ab - ab) + a(c - d)
= 0 + a(c - d) = a(c - d)
5) tự lm