Solve x²-8x+12=0, d²-21d=0 & x²+3x=-2

x²-8x+12=0
d²-21d=0
x²+3x=-2


And please explain, thanks :}

x²-8x+12=0

we factorise to solve ,
(x - 6 )(x-2) = 0 which means that x-6 = 0 and x-2 = 0 ... so x = 6 and x = 2

d²-21d=0
=
d²= 21d divid both sides by d
d = 21

x²+3x=-2

factorise .. but first .. rearrange the equation .. x²+3x +2 = 0

(x + 2) (x + 1 ) = 0 ... which means x = -2 and x = -1

:)

x^2 - 8x + 12 = 0
(x - 6)(x - 2) = 0
x = {2, 6}

d^2 - 21d = 0
d(d - 21) = 0
d = {0, 21}

x^2 + 3x = -2
x^2 + 3x + 2 = 0
(x + 2)(x + 1) = 0
x = {-1, -2}