Question

calcule :
c) 10y-5 (1-y)-3 (2y-2)-20
d) x(x+4)+x (x+2)=2x^(2)+12
e) (x-5)÷10+(1-2x)÷5=(3-x)÷4
f) 4x (x+6)-x^(2)=5x^(2)

Answer 1

2) a) 18x = 65 + 43
18x = 108
x = 108/18
x = 6 
b) 23x = 14 - 17x + 16
23x + 17x = 30
40x = 30
x = 30/40 = 3/4 
c) 10y - 5 - 5y = 6y - 6 -20
5y - 6y = -26 + 5
-y = -21
y = 21 
d) x² + 4x + x² + 2x = 2x² + 12
2x² + 6x = 2x² + 12
Diminuindo 2x² em ambos os lados:
6x = 12
x = 12/6 = 2 
e) [2(x - 5) + 4(1 - 2x)] / 20 = 5 (3 - x) / 20
2x - 10 + 4 - 8x = 15 - 5x
-6x - 6 = 15 - 5x
-6x + 5x = 15 + 6
-x = 21
x = -21 
f) 4x² + 24x - x² = 5x²
4x² - x² - 5x² = -24x
-2x² = -24x
Dividindo por x em ambos os lados:
-2x = - 24
x = 24/2 = 12
3) (3a + 6) / 8 = (2a + 10) / 6
6 (3a + 6) = 8 (2a + 10)
18a + 36 = 16a + 80
2a = 44
a = 44/2 = 22
4) a) (20 - 8x) / 4x = x/4x
20 - 8x = x
-8x = x – 20
-8x - x = -20
-9x = -20
x = 20/9 
b) 3bx = 7bx + 3bc - 6bc
3bx - 7bx = -3bc
-4bx = -3 bc
x = (3bc/4b)
x = 3c/4