Question

resolva as sequintes equações do 2o grau

x²-3x-4=0
x²-8x+7=0
x²+8x=-16
(X+2)(X+3)=3X+5

Answer 1

x² - 3x - 4 = 0

(-b±√b²-4ac)/2a

-(-3)±√(-3)²-4*1*(-4)/2*1

3±√9+16/2

3±√25/2

3±5/2

x1 = 3+5/2

x1 = 8/2

x1 = 4

x2 = 3-5/2

x2 = -2/2

x2 = -1

S = {4, -1}

x² - 8x + 7 = 0

-(-8)±(√(-8)²-4*1*7)/2*1

8±√64-28/2

8±√36/2

8±6/2

x1 = 8+6/2

x1 = 14/2

x1 = 7

x2 = 8-6/2

x2 = 2/2

x2 = 1

S = {7, 1}

x²+8x = -16

x² + 8x + 16 = 0

(-8±√8²-4*1*16)/2*1

-8±√64-64/2

-8±√0/2

-8/2

x = -4

S = {-4}

(X+2)(X+3)=3X+5

x² + 3x + 2x + 6 = 3x + 5

x²+ 5x + 6 - 3x - 5 = 0

x² + 2x + 1 = 0

(-2 ±√2²-4*1*1)/2*1

-2±√4-4/2

-2±√0/2

-2/2

x = -1

S = {-1}