∫[1,x] f(x) dx = 0.5x⁴
d/dx ∫[1,x] f(x) dx = d/dx 0.5x⁴
f(x) * dx/dx - f(1) * d(1)/dx = 0.5 * 4x³
f(x) = 2x³
2∫[1,2] f(x) dx
= 2∫[1,2] 2x³ dx
= x⁴_[1,2]
= 16 - 1
= 15
追问我的想法错哪?
追答如果你代入x = 2,岂不是变成∫[1,2] f(2) d(2) = 0.5 * 2^4 = 8?
这个是变上限定积分,需要通过求导才能找出f(x)