hglws
幼苗
共回答了16个问题采纳率:93.8% 举报
可惜,楼上解错了.
解联立方程 :y = x + 2 和 y = x² 得:x₁= -1,x₂= 2,y₁= 1,y₂= 4
水平质心位置 Xc:
Xc = [∫(-1⟼2)(x+2-x²)xdx]/[∫(-1⟼2)(x+2-x²)dx]
= [x³/3 + x² - x⁴/4](-1⟼2)/[x²/2 + 2x - x³/3](-1⟼2)
= (9/4)/(9/2)
= 1/2
竖直质心位置 Yc:
Yc = [∫(0⟼1)(根号y-(-根号y))ydy + ∫(1⟼4)(根号y-(y-2))ydy]/(9/2)
= (2/9)[4/5 + 32/5]
= 8/5
= 1.6
1年前
3