(x+y)+(2x+1×2分之1y)+(3x+2×3分之1y)+...+(9x+8乘以9分之1y),并求当x=2,y=9时,求此式的值
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![(x+y)+(2x+1×2分之1y)+(3x+2×3分之1y)+...+(9x+8乘以9分之1y),并求当x=2,y=9时,求此式的值](/uploads/image/z/211560-24-0.jpg?t=%28x%2By%29%2B%282x%2B1%C3%972%E5%88%86%E4%B9%8B1y%EF%BC%89%2B%EF%BC%883x%2B2%C3%973%E5%88%86%E4%B9%8B1y%EF%BC%89%2B...%2B%289x%2B8%E4%B9%98%E4%BB%A59%E5%88%86%E4%B9%8B1y%29%2C%E5%B9%B6%E6%B1%82%E5%BD%93x%3D2%2Cy%3D9%E6%97%B6%2C%E6%B1%82%E6%AD%A4%E5%BC%8F%E7%9A%84%E5%80%BC)
(x+y)+(2x+1×2分之1y)+(3x+2×3分之1y)+...+(9x+8乘以9分之1y),并求当x=2,y=9时,求此式的值
(x+y)+(2x+1×2分之1y)+(3x+2×3分之1y)+...+(9x+8乘以9分之1y),并求当x=2,y=9时,求此式的值
(x+y)+(2x+1×2分之1y)+(3x+2×3分之1y)+...+(9x+8乘以9分之1y),并求当x=2,y=9时,求此式的值
原式=(1+2+3+.+9)+(1+1/2+2/3+.+8/9)y
=45x+(13/6+3/4+4/5+5/6+...+8/9)y
=45x+ (3+3/4+7/8+4/5+...+8/9)y
=45x+(3+31/18+139/56+4/5)y
=45x+(3+13/8+1+23/35+8/9)y
=45x+(5+1+79/280+8/9)y
=45x+(6+79/280+8/9)y
=45*2+(6+79/280+8/9)*9
=90+(54+8+711/280)
=152+2+151/280
=154+151/280
153又40分之33
原式=(1+2+3+。。。+9)+(1+1/2+2/3+。。。+8/9)y
=45x+(13/6+3/4+4/5+5/6+...+8/9)y
=45x+ (3+3/4+7/8+4/5+...+8/9)y
=45x+(3+31/18+139/56+4/5)y
...
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原式=(1+2+3+。。。+9)+(1+1/2+2/3+。。。+8/9)y
=45x+(13/6+3/4+4/5+5/6+...+8/9)y
=45x+ (3+3/4+7/8+4/5+...+8/9)y
=45x+(3+31/18+139/56+4/5)y
=45x+(3+13/8+1+23/35+8/9)y
=45x+(5+1+79/280+8/9)y
=45x+(6+79/280+8/9)y
=45*2+(6+79/280+8/9)*9
=90+(54+8+711/280)
=152+2+151/280
=154+151/280
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