cmr (a-b+c) - (a+c)=-b
ai trả lời được là mình đánh dấu lun
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\(\frac{a}{b}=\frac{c}{d}\)
=> \(\frac{a}{c}=\frac{b}{d}=>\frac{a^2}{c^2}=\frac{c^2}{d^2}=\frac{a.b}{b.c}=\frac{a}{c}\)
=> \(\frac{a^2+b^2}{b^2+c^2}=\frac{a}{c}\)
=> dpcm
a) 327+48+73+12
= ( 327 + 73 ) + ( 48 + 12 )
= 300 + 100
= 400
b) 4.5.25.24
= ( 4.25).(5.24)
= 100 . 120
= 12000
c) 30.19+30.81
= 30.(19 + 81 )
= 30.100
= 3000
d) 27.48+27.50+54
=27.48 + 27.50 + 27.2
= 27.(48 + 50 + 2)
= 27.100
= 2700
e) 36.67+18.66
= 36.67 + 18.2.33
= 36.67 + 36.33
= 36.(67 + 33)
= 36.100
= 3600
Chúc bạn học tốt! (^ _ ^)
10. In America, soccer is the usual word for…………..
A. volleyball B. football C. basketball D. baseball
11.…………..does the plane fly? It flies at 500 miles an hour.
A. How much B. How fast C. How D. How long
12. Hoa’s brother is a…………..He repairs cars in a garage.
A. writer B. mechanic C. journalist D. farmer
13. He looks so…………... His face turns red when he talks with strangers.
A. friendly B. creative C. clever D. shy
14. How many………….. are there in your house?
A. kitchen B. room C. rooms D. living room
15. He wears thick…………... They make him so intelligent.
A. shoulders B. tails C. glasses D. necks
16. She has…………..books than Linh.
A. much B. more C. most D. many
17. She’s very beautiful. She has long black…………..and brown…………..
A. face/fingers B. hair/ eyes C. nose/foots D. arm/ears
18. Let’s…………..to Huong’s house.
A. come B. to come C. comes D. coming
19. What…………..great idea!
A. a B. Ø C. the D. an
a) ( 2x + 3)^2 = 121
2x + 3^2 = 121
2x + 9 = 121
2x = 121 - 9
2x = 112
x = 112 : 2
x = 56
Mấy câu sau tự làm nhé bạn
a) (2x + 3)2 = 121
(2x + 3)2 = 112
=> 2x + 3 = 11
2x = 11 - 3
2x = 8
x = 8 : 2
x = 4
b) (75 - 3x)3 = 27
( 75 - 3x)3 = 33
=> 75 - 3x = 3
3x = 75- 3
3x = 72
x = 72 : 3
x = 24
Đặt a/b=c/d=k
=>a=bk; c=dk
\(\dfrac{a+2b}{a}=\dfrac{bk+2b}{bk}=\dfrac{k+2}{k}\)
\(\dfrac{c+2d}{c}=\dfrac{dk+2d}{dk}=\dfrac{k+2}{k}\)
=>\(\dfrac{a+2b}{a}=\dfrac{c+2d}{c}\)
Ta có a+2/b+2 = a/b+2 + 2/b+2 = a(b+2)/b+2 + 2(b+2)/b+2 = a+2
Do a+2 > a/b => a+2/b+2 >a/b
mik làm đại ko bik đúng hay sai đâu nha
Xét tích : \(a\left(b+2\right)=ab+2a\)
\(b\left(a+2\right)=ab+2b\)
Nếu \(a>b\)thì \(ab+2a>ab+2b\)
hay \(a\left(b+2\right)>b\left(a+2\right)\)
\(\Rightarrow\frac{a}{b}>\frac{a+2}{b+2}\)
Nếu \(a< b\)thì \(ab+2a< ab+2b\)
hay \(a\left(b+2\right)< b\left(a+2\right)\)
\(\Rightarrow\frac{a}{b}< \frac{a+2}{b+2}\)
Nếu \(a=b\)thì \(ab+2a=ab+2b\)
hay \(a\left(b+2\right)=b\left(a+2\right)\)
\(\Rightarrow\frac{a}{b}=\frac{a+2}{b+2}\)
= a - b + c - a - c
= - b , tick nha
2
tick nha