已知4x-3-6z=0,x+2y-7z=0,求(2x2+3y2+6z2)÷(x2+5y2+7z2)的值
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![已知4x-3-6z=0,x+2y-7z=0,求(2x2+3y2+6z2)÷(x2+5y2+7z2)的值](/uploads/image/z/6854328-0-8.jpg?t=%E5%B7%B2%E7%9F%A54x-3-6z%3D0%2Cx%2B2y-7z%3D0%2C%E6%B1%82%EF%BC%882x2%2B3y2%2B6z2%EF%BC%89%C3%B7%EF%BC%88x2%2B5y2%2B7z2%EF%BC%89%E7%9A%84%E5%80%BC)
已知4x-3-6z=0,x+2y-7z=0,求(2x2+3y2+6z2)÷(x2+5y2+7z2)的值
已知4x-3-6z=0,x+2y-7z=0,求(2x2+3y2+6z2)÷(x2+5y2+7z2)的值
已知4x-3-6z=0,x+2y-7z=0,求(2x2+3y2+6z2)÷(x2+5y2+7z2)的值
4x-3y-6z=0
x+2y-7z=0
令z=1
4x-3y=6 (1)
x+2y=7 (2)
(2)*4-(1)
11y=22,y=2
则x=3
(2x2+3y2+6z2)÷(x2+5y2+7z2)
=1
4x-3y-6z=0,x+2y-7z=0联立解得:
x=3z, y=2z
(2x2+3y2+6z2)÷(x2+5y2+7z2)
=(36z^2+12z^2+6z^2)÷(9z^2+20z^2+7z^2)
=(54z^2)÷(36z^2)
=54/36
=3/2
联立前两个方程得 x=3z,y=2z
代入2x²+3y²+6z²)\(x²+5y²+7z²)中
则原式=[2×(3z)²+3×(2z)²+6z²]/[(3z)²+5×(2z)²+7z²]
=36z²/36z²
=1