a) (x-6)^2=(x+9)^2
x^2 - 12x + 36 = x^2 + 18x + 81
x^2 - 12x + 36 - x^2 -18x - 81 = 0
-30x = 81 - 36
-30x = 45
x = -1,5
б) x^2+3-54=0
По Дискриминанту
D = b^2-4ac = 3^2 - 4*1*(-54) = 9+216=225
x1 = -b + √D/2a = -3 + 15/2 = 6
x2 = -b - √D/2a = -3 - 15/2 = -9
в) -5x^2-9x=0
x(-5x-9)=0
x=0 или -5x-9=0
-5x=9
x= -1,8
г) x^2-16=0
(x-4)(x+4)=0
x-4=0 или x+4=0
x = 4 x = -4
д) x^2+8x=-12
x^2+8x+12=0
По Дискриминанту
D = b^2-4ac = 8^2 - 4*1*12=64-48=16
x1 = -b + √D/2a = -8+4/2= -2
x2 = -b - √D/2a = -8-4/2= -6
е) x^2-54=-3x
x^2+3x-54=0
По Дискриминанту
D = b^2-4ac = 3^2-4*1*(-54)=9+216=225
x1 = -b + √D/2a = -3+15/2= 6
x2 = -b - √D/2a = -3-15/2=-9