F.1 Maths 代數 (algebra)

1.(2-x)/3-(x+1)/5=1/3
(2 – x)/3 * 15 - (x + 1)/5 * 15 = 1/3 * 15
10 - 5x - 3x - 3 = 5
10 - 3 - 5 = 5x + 3x
2 = 8s
¼ = x
x = ¼

2.y/4-[2(y-9)]/3=(5y+8)/6
y/4 * 12 - [2(y - 9)] /3 * 12 = (5y + 8)/6 * 12
3y - 8y + 72 = 10y + 16
72 - 16 = 10y - 3y + 8y
56 = 15y
56/15 = y
y = 56/15
y = 3 11/15

3.2(x+1)-x-1/2=2x/5-(x-4)
2(x + 1) * 10 - x * 10 - ½ * 10 = 2x/5 * 10 - (x - 4) * 10
20x + 20 - 10x - 5 = 4x - 10x + 40
20x - 10x - 4x + 10x = 40 - 20 + 5
16x = 25
x = 25/16
x = 1 9/16

4.5x-2x-1/5=3x/4+9x-6/2
5x * 20 - 2x * 20 - 1/5 * 20 = 3x/4 * 20 + 9x * 20 - 6/2 * 20
100x - 40x - 4 = 15x + 180x - 60
-4 + 60 = 15x + 180x - 100x + 40x
56 = 135x
56/135 = x
x = 56/135

5.3/5(x-7)-2/3(x/2-8)=4+1/15(2x+1)
3/5(x - 7) * 15 - 2/3(x/2 - 8) * 15 = 4 * 15 + 1/15(2x + 1) * 15
9x - 63 - 5x + 80 = 60 + 2x + 1
9x - 5x - 2x = 60 + 1 + 63 - 80
2x = 44
x = 22