a)4/x=5/9 | * 9x 36 = 5x |:5 x = 5 ⅕ b)x/12=1,2/4 | *12 x = 3,6 c)3,2/2,8=x/3,5 | *9,8 11,2 = 2,8x | :2,8 x = 4 d)9,36/7,2=1,3/x |*7,2x 9,36x = 9,36 | : 9,36 x = 1 e)0,6/x=0,8/6 | * 6x 3,6 = 0,8x | : 0,8 x = 4,5 f)x/0,6=6/0,8 | * 0,48 0,8x = 3,6 | : 0,8 x = 4,5 g)x-5/7=3/5 | * 35 35x - 25 = 21 | +25 35x = 46 | : 35 x = 1,31 h)x/3=x+5/2 | * 6 2x = 6x +15 |-6x -4x = 15 | : (-4) x = -3,75 i)4/x+6=5/7+x | * 7x 28 + 42x = 5x + x² | - 5x - x² - 28 37x - x² = -28 x (37 - x) = - 28 | : (37 - x) x = -28/(37-x)
a)4/x=5/9 5x = 4*9 5x = 36 x = 36/5 x = 7,2 b)x/12=1,2/4 4x = 1,2*12 4x = 144/10 /:4 x = 36/10 x = 3,6 c)3,2/2,8=x/3,5 2,8x = 3,2*3,5 2,8x = 56/5 /:2,8 x = 28/7 x = 4 d)9,36/7,2=1,3/x 9,36x = 1,3*7,2 9,36x = 234/25 /:9,36 x = 936/936 x = 1 e)0,6/x=0,8/6 0,8x = 6*0,6 0,8x = 3,6 /:0,8 x = 9/2 x = 4,5 f)x/0,6=6/0,8 0,8x = 6*0,6 0,8x = 3,6 /:0,8 x = 9/2 x = 4,5 g)x-5/7=3/5 5(x-5) = 3*7 5x-25 = 21 5x = 21+25 5x = 46 /:5 x = 9,2 h)x/3=x+5/2 3(x+5) = 2x 3x+15 = 2x 3x-2x = -15 x = -15 i)4/x+6=5/7+x 5(x+6) = 4(7+x) 5x+30 = 28+4x 5x-4x = 28-30 x = -2
