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a là 8/1 :b là 15/18 nha!

ta có :

\(\hept{\begin{cases}A=\frac{64}{7}:\frac{8}{7}=\frac{64}{7}\times\frac{7}{8}=8\\B=\frac{15}{3}\times\frac{3}{8}=\frac{15}{8}\end{cases}}\) nên \(A:B=8:\frac{15}{8}=\frac{64}{15}\)

câu trả lời của bạn Nguyễn Minh Quang dr nha

cậu k đi chơi trung thu à

Ko mìk ko đi chơi bạn giải dc câu nào ko giải giúp mìk vs

a: =-5/9-4/9+8/15+7/15-2/11=-2/11

b: =10/17+7/17-5/13-8/13+11/25

=11/25

c: =(9/12-2/12)*3/2=7/12*3/2=21/24=7/8

d: =(31/10-25/10)*3-2

=3/5*3-2

=9/5-2

=-1/5

\(\dfrac{7}{15}+\left(\dfrac{-4}{11}\right)+\dfrac{8}{15}-2,5+\dfrac{7}{15}\)

\(=\dfrac{7}{15}+\left(\dfrac{-4}{11}\right)+\dfrac{8}{15}+\left(\dfrac{-5}{2}\right)+\dfrac{7}{15}\)

\(=\left(\dfrac{7}{15}+\dfrac{8}{15}+\dfrac{7}{15}\right)+\left[\left(\dfrac{-4}{11}\right)+\left(\dfrac{-5}{2}\right)\right]\)

\(=\dfrac{22}{15}+\left(\dfrac{-63}{22}\right)\)

\(=\dfrac{-461}{330}\)

\(=\dfrac{7}{15}+\dfrac{8}{15}+\dfrac{-4}{11}-\dfrac{5}{2}+\dfrac{7}{15}=\dfrac{22}{15}-\dfrac{63}{22}=-\dfrac{461}{330}\)

=7/15+8/15+(−4)/11−5/2+7/15=(22/15−63/22)=(−461)/330

a) 6x-7 +15= 7x-63 +53

6x+8= 7x-10

8+10= 7x-6x

18= x

b) 120:(-12) +2(x+3)= 4.(-8)

-10+2x+6=(-32)

-4+2x=-32

2x=-28

x= -14

6x-7 +15= 7(x-9)+53

=>6x-7+15=7x-63+53

=>6x-7x=-63+53+7-15

=>-x=-18

=>x=18

Bài 8:

a: Khi a=1 thì phương trình sẽ là \(\left(1-4\right)x-12x+7=0\)

=>-3x-12x+7=0

=>-15x+7=0

=>-15x=-7

hay x=7/15

b: Thay x=1 vào pt, ta được:

\(a^2-4-12+7=0\)

\(\Leftrightarrow\left(a-3\right)\left(a+3\right)=0\)

hay \(a\in\left\{3;-3\right\}\)

c: Pt suy ra là \(\left(a^2-16\right)x+7=0\)

Để phương trình đã cho luôn có một nghiệm duy nhất thì (a-4)(a+4)<>0

hay \(a\notin\left\{4;-4\right\}\)

Để \(2x^3-4x^2+6x+a⋮x+2\)

\(\Leftrightarrow2x^3-4x^2+6x+a=\left(x+2\right)\cdot a\left(x\right)\)

Thay \(x=-2\)

\(\Leftrightarrow2\left(-2\right)^3-4\left(-2\right)^2+6\left(-2\right)+a=0\\ \Leftrightarrow-16-16-12+a=0\\ \Leftrightarrow-44+a=0\Leftrightarrow a=44\)

a).\(\dfrac{x}{15}\)=\(\dfrac{4}{3}\)\(\Leftrightarrow\)x.3=15.4\(\Leftrightarrow\)3x=60\(\Leftrightarrow\)x=20

b)x:\(\dfrac{4}{3}\)=\(\dfrac{5}{6}\)\(\Leftrightarrow\)\(\dfrac{3x}{4}=\dfrac{5}{6}\)\(\Leftrightarrow\)3x.6=4.5\(\Leftrightarrow\)18x=20\(\Leftrightarrow\)\(\dfrac{10}{9}\)

c)\(\dfrac{7}{2}\)-x=\(\dfrac{5}{6}\)\(\Leftrightarrow\)\(\dfrac{7}{2}-\dfrac{2x}{2}\)=\(\dfrac{5}{6}\)\(\Leftrightarrow\)\(\dfrac{7-2x}{2}\)=\(\dfrac{5}{6}\)\(\Leftrightarrow\)(7-2x).6=2.5\(\Leftrightarrow\)42-12x=10

\(\Leftrightarrow\)-12x=-32\(\Leftrightarrow\)x=\(\dfrac{8}{3}\)