Question

Resolva as equações:
a) 2x + 15 = 35
b) 4 - 3x = 19
c) 3( x - 10) = 2x
d) x2 - 4x + 3 = 0
e) x2 - 4 = 0
f) x2 - 6x =0

Answer 1

Resposta:

a) 2x + 15 = 35

2x = 35 - 15

2x = 20

x = 20/2

x = 10

b) 4 - 3x = 19

4 = 19 + 3x

4 - 19 = 3x

3x = -15

x = -15/3

x = -5

c) 3(x - 10) = 2x

3x - 30 = 2x

3x - 2x = 30

x = 30

d) x² - 4x + 3 = 0

a = 1, b = -4, c = 3

$x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}\\x=\dfrac{-(-4)\pm\sqrt{(-4)^2-4\cdot1\cdot3}}{2\cdot1}\\\\x=\dfrac{4\pm\sqrt{16-12}}{2}\\\\x=\dfrac{4\pm\sqrt{4}}{2}\\\\x=\dfrac{4\pm2}{2}\\\\x_1=\dfrac{4+2}{2}=\dfrac{6}{2}=3\\\\x_2=\dfrac{4-2}{2}=\dfrac{2}{2}=1$

e) x² - 4 = 0

x² = 4

x = ±√4

x = ±2

f) x² - 6x =0

x (x - 6) = 0

x₁ = 0

x₂ - 6 = 0

x₂ = 6