Answer:

1. x^2 - 81 = 0

x^2 = 81

√x^2 = √81

x = 9

x = -9

2. x^2 + 5x = 0

(x+2)(x+3) = 0

x = -2 , x = -3

3. x^2 - 4 + 3 = 0

(x-3)(x-1)=0

x=3 , x=1

Answer:

1. x²-81=0

transpose -81 to the other side, so it'll look like this,

x²=81

(that becomes positive when you will transpose it to the other side)

to get the value of x, find the roots of 81.

√x² = √81

(square root if the x has an exponent which 2)

Therefore, x= ±9. (because 9•9 is 81)

2. x²+5x+6=0

factor the equation.

(x+3) (x+2)

x+3=0

x = -3

x+2=0

x = -2

(To check if it's true, just substitute the value of x on the equation).