若△为某种新运算,设A△B=A^2-AB,试求（-2）△（x-1）=3.5中x的值_数学解答

若△为某种新运算,设A△B=A^2-AB,试求（-2）△（x-1）=3.5中x的值

人气：131 ℃　时间：2020-05-01 02:02:45

解答

（-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