考虑函数f(x) = 2x^2 - 4x + 9. 评估2f(3) + 3f(-3).
给出函数f(x) = 2x^2 - 4x+9,我们需要评估2f(3) + 3f(-3.首先,我们计算f(3) 和f(-3):f(3) = 2(3^2) - 4*3 + 9 = 15 f(-3) = 2(-3)^2 - 4(-3) + 9 = 39 替换这些值,我们得到: 2f(3) + 3f(-3) = 2(15) + 3(39) = 30 + 117 = 147.因此,2f3) + 3f-3) = 147.