Áp dụng tính chất dãy tỉ số bằng nhau:\(\dfrac{\left(5z-3y\right)+\left(3x-2z\right)+\left(2y-5x\right)}{2+5+3}\)

=\(\dfrac{\left(3x-5x\right)+\left(-3y+2y\right)+\left(5z-2z\right)}{2+5+3}\)

=\(\dfrac{-2x-y+3z}{2+5+3}\)(???!!!!)

=\(\dfrac{-2x}{2}=\dfrac{-y}{5}=\dfrac{3z}{3}\)

=\(\dfrac{2}{-2x}=\dfrac{5}{-y}=\dfrac{3}{3z}\)

tớ xin chịu trận vì ko chứng minh được :(((

nó lại ra như thế này

\(\dfrac{19\times2\times5}{19\times3\times5}=\dfrac{2}{3}\)

đúng òi

247 X 328 = 81016

35864:175= 35864/175

\(\dfrac{7}{5}x\dfrac{2}{5}=\dfrac{14}{25}\)

\(\dfrac{3}{4}+\dfrac{5}{4}:\dfrac{1}{4}x\dfrac{1}{2}=\dfrac{3}{4}+5x\dfrac{1}{2}=\dfrac{5}{2}\)

7/5 x 2/5 = 14/25

3/4 + 5/4 : 1/4 x 1/2 = 13/4

125/90=25/18

84/91=12/13

75/45=25/15=5/3

125/90=25/18

84/91=12/13

75/45=25/15=5/3

6/7=18/21=54/63=104/126

125/90 = 25/18 

84/91 = 12/13

75/45 = 25/15 = 5/3

6/7 = 18/21 = 54/63 = 108/126

đề:)?

quy đồng à

a: 9/7>1>5/6

b: 4/7=12/21>8/21

c: 2/5=12/30

1/3=10/30

1/2=15/30

mà 10<12<15

nên 1/3<2/5<1/2

\(\dfrac{13}{50}+9\%+\dfrac{41}{100}+0,24\)
\(=\dfrac{26}{100}+\dfrac{9}{100}+\dfrac{41}{100}+\dfrac{24}{100}\)
\(=\left(\dfrac{26}{100}+\dfrac{24}{100}\right)+\left(\dfrac{9}{100}+\dfrac{41}{100}\right)\)
\(=\dfrac{1}{2}+\dfrac{1}{2}\)
\(=1\)

\(\dfrac{7}{9}< \dfrac{x}{y}< \dfrac{7}{8}\)

\(\dfrac{56}{72}< \dfrac{x}{y}< \dfrac{63}{72}\)

\(\dfrac{x}{y}=\left\{\dfrac{57}{72};\dfrac{58}{72};\dfrac{59}{72};\dfrac{60}{72};\dfrac{61}{72};\dfrac{62}{72}\right\}\)

\(a)P\left(x\right)=5x^5+3x-4x^4-2x^3+6+4x^2\)

   \(P\left(x\right)=5x^5-4x^4-2x^3+4x^2+3x+6\)

\(Q\left(x\right)=2x^4-x+3x^2-2x^3+\dfrac{1}{4}-x^5\)

\(Q\left(x\right)=-x^5+2x^4-2x^3+3x^2-x+\dfrac{1}{4}\)

\(a)P\left(x\right)-Q\left(x\right)=\left(5x^5-4x^4-2x^3+4x^2+3x+6\right)+\left(-x^5+2x^4-2x^3+3x^2-x+\dfrac{1}{4}\right)\)

\(P\left(x\right)-Q\left(x\right)=5x^5-4x^4-2x^3+4x^2+3x+6+x^5-2x^4+2x^3-3x^2+x-\dfrac{1}{4}\)

\(P\left(x\right)-Q\left(x\right)=\left(5x^5+x^5\right)+\left(-4x^4-2x^4\right)+\left(-2x^3+2x^3\right)+\left(4x^2-3x^2\right)+\left(3x+x\right)+\left(6-\dfrac{1}{4}\right)\)

\(P\left(x\right)-Q\left(x\right)=6x^5-6x^4+x^2+4x+\dfrac{23}{4}\)

\(\text{c)Thay x=-1 vào biểu thức P(x),ta được:}\)

\(P\left(x\right)=5.\left(-1\right)^5-4.\left(-1\right)^4-2.\left(-1\right)^3+4.\left(-1\right)^2+3.\left(-1\right)+6\)

\(P\left(x\right)=\left(-5\right)-4-\left(-2\right)+4+\left(-3\right)+6\)

\(P\left(x\right)=\left(-9\right)-\left(-2\right)+4+\left(-3\right)+6\)

\(P\left(x\right)=\left(-7\right)+4+\left(-3\right)+6\)

\(P\left(x\right)=\left(-3\right)+\left(-3\right)+6\)

\(P\left(x\right)=\left(-6\right)+6=0\)

\(\text{Vậy giá trị của P(x) tại x=-1 là:0}\)

\(\text{Vậy =-1 là nghiệm của P(x)}\)

\(\text{Thay x=-1 vào biểu thức Q(x),ta được:}\)

\(Q\left(x\right)=\left(-1\right).5+2.\left(-1\right)^4-2.\left(-1\right)^3+3.\left(-1\right)^2-\left(-1\right)+\dfrac{1}{4}\)

\(Q\left(x\right)=\left(-5\right)+2-\left(-2\right)+3-\left(-1\right)+\dfrac{1}{4}\)

\(Q\left(x\right)=\left(-3\right)-\left(-2\right)+3-\left(-1\right)+\dfrac{1}{4}\)

\(Q\left(x\right)=\left(-5\right)+3-\left(-1\right)+\dfrac{1}{4}\)

\(Q\left(x\right)=\left(-2\right)-\left(-1\right)+\dfrac{1}{4}\)

\(Q\left(x\right)=\left(-3\right)+\dfrac{1}{4}=\dfrac{-13}{4}\)

\(\text{Vậy x=-1 không phải là nghiệm của Q(x)}\)

\(\text{d)Thay x=-1 vào biểu thức }P\left(x\right)-Q\left(x\right),\text{ta được:}\)

\(P\left(x\right)-Q\left(x\right)=6.\left(-1\right)^5-6.\left(-1\right)^4+\left(-1\right)^2+4.\left(-1\right)+\dfrac{23}{4}\)

\(P\left(x\right)-Q\left(x\right)=\left(-6\right)-6+1+\left(-4\right)+\dfrac{23}{4}\)

\(P\left(x\right)-Q\left(x\right)=\left(-12\right)+1+\left(-4\right)+\dfrac{23}{4}\)

\(P\left(x\right)-Q\left(x\right)=\left(-11\right)+\left(-4\right)+\dfrac{23}{4}\)

\(P\left(x\right)-Q\left(x\right)=\left(-15\right)+\dfrac{23}{4}=\dfrac{-37}{4}\)

\(\text{Vậy giá trị của P(x)-Q(x) tại x=-1 là:}\dfrac{-37}{4}\)

a: =-7/25-8/25=-15/25=-3/5

b: =-3/4-5/7=-21/28-20/28=-41/28