a.\(\dfrac{27}{8}\)

b.\(\dfrac{37}{40}\)
c.\(\dfrac{5}{2}\)

d.\(\dfrac{7}{3}\)

e.5

g.\(\dfrac{53}{16}\)

Bài 1 :

a) \(\dfrac{3}{2}+\dfrac{5}{4}+\dfrac{5}{8}=\dfrac{12}{8}+\dfrac{10}{8}+\dfrac{5}{8}=\dfrac{12+10+5}{8}=\dfrac{27}{8}\)

b) \(\dfrac{4}{5}-\dfrac{3}{8}+\dfrac{2}{4}=\dfrac{32}{40}-\dfrac{15}{40}+\dfrac{20}{40}=\dfrac{32-15+20}{40}=\dfrac{37}{40}\)

c) \(3+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{3}{1}+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{24}{8}+\dfrac{6}{8}-\dfrac{10}{8}=\dfrac{20}{8}=\dfrac{5}{2}\)

d) \(\dfrac{5}{6}-\dfrac{1}{2}+2=\dfrac{5}{6}-\dfrac{1}{2}+\dfrac{2}{1}=\dfrac{5}{6}-\dfrac{3}{6}+\dfrac{12}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)

e) \(\dfrac{3}{5}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{2}{5}+\dfrac{16}{11}+\dfrac{19}{13}=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)=1+2+2=5\)

g) \(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}=\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{13}{32}=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{29}{32}+\dfrac{13}{32}\right)=1+1+\dfrac{21}{16}=2+\dfrac{21}{16}=\dfrac{53}{16}\)

a,3/2+5/4+5/8 = 12/8 + 10/8 + 5/8 = 27/8

b,4/5-3/8+2/4 = 32/40 - 15/40 + 20/40 = 37/40

c,3+6/8-5/4= 24/8 + 6/8 - 10/8 = 20/8 = 5/2

d,5/6-1/2+2 = 5/6 - 3/6 + 12/6 = 14/6 = 7/3

e,3/5+6/11+7/13+2/5+16/11+19/13 = ( 3/5+ 2/5) + ( 6/11 + 16/11) + ( 7/13 + 19/13) = 1 + 2 + 2 = 5

g,75/100+18/21+29/32+1/4+3/21+13/32 = 3/4 + 6/7 + 29/32 + 1/4 + 1/7 + 13/32=  ( 3/4 + 1/4) + ( 29/32 + 13/32) + ( 6/7 + 1/7)= 1 + 21/16 + 1 = 53/16

#maianhhomework

câu 1 : tìm a biết

a + b _c = 18 với b = 10 ; c = - 9

\(\Rightarrow a+10+9=18\)

\(a=18-19=-1\)

2a _ 3b + c = 0 với b = -2 ; c= - 4

\(2a+6-4=0\)

\(2a+2=0\)

\(2a=-2\)

\(a=-1\)

3a _ b _ 2c = 2 với b = 6 ; c = - 1

\(3a-6+2=2\)

\(3a-8=2\)

\(3a=10\)

\(a=\frac{10}{3}\)

12 _ a + b + 5c = - 1 với b = - 7 ; c = 5

\(12-a-7+25=-1\)

\(12-a-7=-26\)

\(12-a=-19\)

\(a=31\)

1 _ 2b + c _ 3a = -9 với b = -3 ; c = 7

\(1+6+7-3a=-9\)

\(14-3a=9\)

\(3a=5\)

\(a=\frac{5}{3}\)

câu 2 : sắp xếp theo thứ tự

* tăng dần

a) 7 ; 12 ; + 4 ; 0 dấu giá trị tuyệt đối - 8 dgttđ ; - 10 ; 1

Có : \(7;12;4;0;8;-10;1\)

Sắp xếp : \(-10;0;1;4;7;8;12\)

b) - 12 ; dấu giá trị tuyệt đối + 4 dgttđ  ;- 5 ; - 3 ; + 3 ; 0 ; dấu giá trị tuyệt đối - 5 dgttđ

Có : \(-12;4;-5;-3;3;0;5\)

Sắp xếp : \(-12;-5;-3;0;3;4;5\)

* giảm dần

a ) + 9 ; - 4 ; dấu giá trị tuyệt đối - 6 dgttđ ; 0 ; - dấu giá trị tuyệt đối - 5 dgttđ ; - ( -12 )

Có : \(9;-4;6;0;-5;12\)

Sắp xép : \(12;9;6;5;0;-4\)

b ) - ( -3 ) ; - ( + 2 ) ; dấu giá trị tuyệt đối - 1 dgttđ ; 0 ; + ( - 5 ) ; 4 ; dấu giá trị tuyệt đối + 7 dgttđ ; -8

Có : \(3;-2;1;0;-5;4;7;-8\)

sắp xếp : \(7;4;3;1;0;-3;-5;-8\)

\(a,=4x^2+4x+1\\ b,=9-12y+4y^2\\ c,=\dfrac{x^2}{4}-xy+y^2\\ d,=\dfrac{25}{4}-5x+x^2\\ e,=4x^2+32xy+64y^2\\ f,=9x^2-30xy+25y^2\)

a. (2x + 1)² 

= 4x² + 4x + 1

b. (3 - 2y)²

= 9 - 12y + 4y²

- Các câu còn lại bn dung CT: (A + B)² = A² + 2AB + B² và (A - B)² = A² - 2AB + B² để tính tiếp nha, phân số cũng đc tính.)

a) 4x^2 + 4x + 1

b) 4y^2 - 12y + 9

c) x^2/4 - xy + y^2

d) x^2 - 5x + 25/4

e) 4x^2 + 32xy + 64y^2

f) 9x^2 - 30xy + 25y^2

quy luat khi tim x la :lam cac phep tinh +,- truoc nhan, chia sau

lay -7/3 - -4/3=-1

sau do lay -1x-5/3=-5/3

cac bai kia ban lam tuong tu/con rieng gia tri tuyet doi ban phai xet theo tinh chat cua no

`@` `\text {Ans}`

`\downarrow`

`3^3 * x^2 - 2^4 * x^2 = 8^2 * 5 - 4^2 * 3^2`

`=> x^2 . (3^3 - 2^4) = 2^6 . 5 - 2^4 . 3^2`

`=> x^2 . 11 = 2^4 . (2^2 . 5 - 3^2)`

`=> x^2 . 11 = 2^4 . 11`

`=> x^2 . 11 - 2^4 . 11 = 0`

`=> 11 . (x^2 - 16) = 0`

`=> x^2 - 16 = 0`

`=> x^2 = 16`

`=> x^2 = (+-4)^2`

`=> x = `\(\pm4\)

Vậy, `x \in`\(\left\{4;-4\right\}\)

_____

\(\left[\left(\dfrac{1}{2}\right)^2-\left(\dfrac{1}{3}\right)^3\right]x+3^2\cdot2^2=4^2\cdot3\)

`=>`\(\left(\dfrac{1}{4}-\dfrac{1}{27}\right)x+\left(3\cdot2\right)^2=48\)

`=>`\(\dfrac{23}{108}\cdot x+6^2=48\)

`=>`\(\dfrac{23}{108}x=48-6^2\)

`=>`\(\dfrac{23}{108}x=48-36\)

`=>`\(\dfrac{23}{108}x=12\)

`=>`\(x=\dfrac{1296}{23}\)

Vậy, `x = `\(\dfrac{1296}{23}\)

\(3^3.x^2-2^4.x^2=8^2.5-4^3.3^2\)

\(\Leftrightarrow x^2\left(27-16\right)=2^6.5-2^6.9\)

\(\Leftrightarrow11x^2=2^6.\left(5-9\right)=-4.2^6=-2^8\)

\(\Leftrightarrow x^2=-\dfrac{2^6}{11}< 0\)

\(\Rightarrow x\in\varnothing\)

\(\left[\left(\dfrac{1}{2}\right)^2-\left(\dfrac{1}{3}\right)^3\right]x+3^2.2^2=4^2.3\)

\(\Leftrightarrow\left(\dfrac{1}{4}-\dfrac{1}{27}\right)x+36=48\)

\(\Leftrightarrow\dfrac{23}{108}x=12\Leftrightarrow x=\dfrac{12.108}{23}=\dfrac{1296}{23}\)