Answer:
If we do square on both sides we get two answers i.e. (x+12)^2=(3x+20)^2
(x^2)+24x+144=(9x^2)+120x+400
(8x^2)+96x+256=0
(x^2)+12x+32=0
(x+4)(x+8)=0
x= -4 or x= -8.
Else we have another method
x+12=3x+20
x+12–20=3x
x-8=3x,
Now square on both sides.
(x-8)^2=(3x)^2
x^2–16x+64=(9x^2)
(9x^2)-(x^2)+16x-64=0
(8x^2)+16x-64=0
(x^2)+2x-8=0
(x+4)(x-2)=0
x= -4 or x= 2.
But It Didn’t Satisfy for The Equation When
x=2 or x= -8,So The Value of x will be -4 which satisfies given question.