27^(2x+12)=3^(4x(x-1))
(3^3)^(2x+12)=3^(4x(x-1))
3^(6x+36)=3^(4x^2-4x)
因此6x+36=4x^2-4x
4x^2-10x-36=0
2x^2-5x-18=0
(2x-9)(x+2)=0
x=9/2或-2(-2不合)
2x+12=9+12=21
答案為(B)
27^(2x+12)=3^(4x(x-1))
(3^3)^(2x+12)=3^(4x(x-1))
3^(6x+36)=3^(4x^2-4x)
因此6x+36=4x^2-4x
4x^2-10x-36=0
2x^2-5x-18=0
(2x-9)(x+2)=0
x=9/2或-2(-2不合)
2x+12=9+12=21
答案為(B)
看了這個問題的人
也有瀏覽這些問題喔😉