Question

Resolva as equações a seguir.

a) x²-9=0

b) -x²-9=0

c) x²-90=31

Answer 1

A)

X² - 9 = 0
1X² - 9 = 0
1X² = 0 + 9
1X² = 9
X² = 9/1
X = 9
X = ±√9
X = ±3

S = {-3,3}

B)

-X² - 9 = 0
-1X² - 9 = 0
-1X² = 0 + 9
-1X² = 9
X² = 9 /(-1)
X = -9
X = ±√-9
X = ±3i

S = {-3i,3i}

C)

X² - 90 = 31
1X² - 90 = 31
1X² = 31 + 90
1X² = 121
X² = 121/1
X = 121
X = ±√121
X = ±11

S = {-11,11}