若△为某种新运算,设A△B=A^2-AB,试求（-2）△（x-1）=3.5中x的值
问题描述：
若△为某种新运算,设A△B=A^2-AB,试求（-2）△（x-1）=3.5中x的值
答
（-2）△（x - 1）= 3.5
(-2)² - (-2)(x - 1) = 3.5
4 + 2(x - 1) = 3.5
4 + 2x - 2 = 3.5
2x = 3.5 - 4 + 2
2x = 1.5
x = 1.5÷2
x = 0.75