Question

[Lê Chi]

Bài 1: Tìm x:

a) x15=−23,5" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">x15=−23,5${\displaystyle \frac{x}{15}}={\displaystyle \frac{-2}{3,5}}$

b) 16x=x25" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">16x=x25${\displaystyle \frac{16}{x}}={\displaystyle \frac{x}{25}}$

c) 0,50,7=−0,15x" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">0,50,7=−0,15x${\displaystyle \frac{0,5}{0,7}}={\displaystyle \frac{-0,1}{5x}}$

Bài 2: Lập tất cả các tỉ lệ thức từ bốn số sau :

-25; -2; 4; 50

Bài 3: Tìm x, y, z:

a) x5=y25" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">x5=y25${\displaystyle \frac{x}{5}}={\displaystyle \frac{y}{25}}$ và x+ y = 60

b) $5x=3y$ và x-y = -5

c) x2=y4=z6" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">x2=y4=z6${\displaystyle \frac{x}{2}}={\displaystyle \frac{y}{4}}={\displaystyle \frac{z}{6}}$ và y+z-x = 8

d) x3=y4;y6=z8" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">x3=y4;y6=z8${\displaystyle \frac{x}{3}}={\displaystyle \frac{y}{4}};{\displaystyle \frac{y}{6}}={\displaystyle \frac{z}{8}}$ và x + y - z = 50

e) x3=y4=z5" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">x3=y4=z5${\displaystyle \frac{x}{3}}={\displaystyle \frac{y}{4}}={\displaystyle \frac{z}{5}}$ và 2x + 3y + 5z = 86

f) x : y : z = 2 : 5 : 7 và x + y + z = -28

g) x3=y7=z2" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">x3=y7=z2${\displaystyle \frac{x}{3}}={\displaystyle \frac{y}{7}}={\displaystyle \frac{z}{2}}$ và 2x2+y2+3z2=316" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:20.34px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">2x2+y2+3z2=316${}^{}2x^2+y^2+3z^2=316$

P/s: Giúp mình với các bạn, mình đg rất cần gấp. Thank you