Question

1)108: 90=42: 5х 2)(7х-3)/4 = (5-2х)/6 3)5/2х = 3/(4-х) 5)2/(6-х)= 4/(5х+3)

Answer 1

1. 108:90=42:5х

1.2=$\frac{42}{5}$x

$\frac{5}{42}$*1.2=x

$\frac{5}{42}$*$\frac{6}{5}$=x

$\frac{1}{7}$=x

x=$\frac{1}{7}$

2.(7х-3)/4 = (5-2х)/6

6(7x-3)=4(5-2x)

42x-18=20-8x

42x+8x=20+18

50x=38

x=$\frac{19}{25}$

3. 5/2х = 3/(4-х)

$\frac{5}{2}$x=$\frac{3}{4-x}$, x$\neq$4

5x=$\frac{6}{4-x}$

5x*(4-x)=6

5x*(4-x)-6=0

20x-$5x^{2}$-6=0

-$5x^{2}$+20x-6=0

5x2-20x+6=0

x=$\frac{-(-20)+-\sqrt{(-20)^{2}-4*5*6 } )}{2*5}$

x=$\frac{20+-\sqrt{400-120} }{10}$

x=$\frac{20+-\sqrt{280} }{10}$

x=$\frac{20+-2\sqrt{70} }{10}$

x=$\frac{20+2\sqrt{70} }{10}$  x=$\frac{20-2\sqrt{70} }{10}$

x=$\frac{10+\sqrt{70} }{5}$  x=$\frac{10-\sqrt{70} }{5}$, x$\neq$4

x_{1} =$\frac{10-\sqrt{70} }{5}$ x_{2} =$\frac{10+\sqrt{70} }{5}$

5. 2/(6-х)= 4/(5х+3)

$\frac{2}{6-x} =\frac{4}{5x+3}$, x