Determine as raizes das equações
a)X2 - 8x+12=0
b)2x2 - 7X =15
c)5x2-15=0
d)4 x(x +3)=5x
e)7x= -14%
f)x2 + 2X-8=0
g)4x2+9=12*
h)21 = 7x2
W x (x-3)-2(x-3) = 6
il
Soluções para a tarefa
Resposta:
a)X² - 8x+12=0
a. 1
b. -8
c. 12
x = -b ± √b²-4.a.c/2.a
x = -(-8) ± √(-8)²-4.1.12/2.1
x = 8 ± √64-48/2
x = 8 ± √64-48/2
x = 8 ± √16/2
x = 8 ± 4/2
x₁ = 8+4/2
x₁ = 12/2
x₁ = 6
x₂ = 8-4/2
x₂ = 4/2
x₂ = 2
S= (6,2)
b)2x² - 7X =15 ⇒2x² -7x -15= 0
a. 2
b. -7
c. -15
x = -b±√b² -4.a.c/2.a
x = -(-7)±√(-7)² -4.2.(-15)/2.1
x = 7±√49 +120/2
x = 7±√169/2
x = 7±13/2
x₁ = 7+13/2
x₁ = 20/2
x₁ = 10
x₂ = 7-13/2
x₂ = -6/2
x₂ = -3
S=(3,10)
c)5x²-15=0
x(5x-15) = 0
5x-15=0
5x= 15
x = 15/5
x = 3
S=(0,3)
d)4x(x +3)=5x
4x²+12x -5x=0
x(4x+12-5)=0
4x+12-5=0
4x=-12+5
4x = -7
x= -7/4
S=(0,-7/4)
e)7x= -14%
x = -14%/7
x = -2%
S=(-2%)
f)x² + 2X-8=0
a. 1
b. 2
c. -8
x = -b±√-b-4.a.c/2.a
x = -(2)±√2²-4.1.(-8)/2.1
x = -2±√4+32/2
x = -2±√36/2
x = -2±6/2
x₁ = -2+6/2
x₁ = 4/2
x₁ = 2
x₂ = -2 -6/2
x₂ = -8/2
x₂ = -4
S=(2, -4)
g)4x²+9=12*
4x² = 12-9
4x² = 3
x² = 3/4
x = √3/4 ⇒ √3/√4
x = √3/√2²
x = √3/2
S=(3/4)
h)21 = 7x²
7x² = 21
x² = 21/7
x² = 3
x = √3
S+(√3)
W) x(x-3)-2(x-3) = 6
x²-3x -2x +6 - 6=0
x² -5x +0=0
x² -5x = 0
x(x-5)=0
x-5=0
x=5
S=(0,5)
Explicação passo-a-passo: