初一数学字母选择题

初一数学字母选择题题目：1.若a+b=5，b+c=8，c+a=9，求a+b+c的值。A.15B.16C.17D.182.若x-y=3，2x+3y=5，求2x-y的值。A.1B.2C.3D.43.若2a-4b=-6，a+3b=1，求a+b的值。A.-1B.0C.1D.24.若x–2y=4，y+3z=5，4x–3z=13，求x+z的值。A.7B.8C.9D.105.若2x–3y+4z=5，x+y+2z=3，-x+2y–z=-1，求x+y+z的值。A.0B.1C.2D.36.若3a–2b+5c=10，2a+3b–4c=7，求a-b+c的值。A.2B.3C.4D.57.若m+n=p，n+p=q，p+q=r，求$2r-m$的值。A.-mB.mC.rD.p8.若$x^2+4y^2=25$，$2x+y=7$，求$x-y$的值。A.-2B.-1C.0D.19.若$\frac{x}{y}=\frac{3}{2}$，$\frac{x+z}{y}=4$，$\frac{y-z}{x-y}=1$，求$\frac{x-z}{2z}$的值。A.$\frac{1}{4}$B.$\frac{1}{3}$C.$\frac{1}{2}$D.$\frac{2}{3}$10.若$2x-y=4$，$3y-z=5$，$x+z=3$，求$xy-z$的值。A.5B.6C.7D.811.若$\sqrt{a}+b=7$，$\sqrt{b}+c=8$，$\sqrt{c}+a=9$，求$\sqrt{a}+\sqrt{b}+\sqrt{c}$的值。A.10B.12C.14D.1612.若$\sqrt{x}+\sqrt{y}=6$，$\sqrt{y}+\sqrt{z}=7$，$\sqrt{z}+\sqrt{x}=8$，求$\sqrt{x}+\sqrt{y}+\sqrt{z}$的值。A.15B.16C.17D.1813.若$a+b=5$，$b+c=6$，$c+a=7$，求$a^3+b^3+c^3$的值。A.99B.100C.101D.10214.若$a-b=6$，$b-c=9$，$c-a=-15$，求$a^2+b^2+c^2$的值。A.22B.38C.56D.7415.若$a+b=7$，$b+c=8$，$c+d=9$，求$a^2+b^2+c^2+d^2$的值。A.105B.112C.119D.126（题目省略，答案如下）答案：1.A2.A3.C4.A5.C6.B7.C8.A9.D10.C11.B12.C13.B14.D15.C16.A17.B18.D19.C20.A21.B22.C23.C24.A25.C26.B27.D28.C29.A30.D31.B32.B33.C34.D35.A36.C37.B38.D39.B40.D41.A42.C43.A44.D45.B46.A47.C48.D49.B50.A51.C52.B53.C54.D55.C56.A57.B58.A59.D60.A61.C62.B63.D64.A65.C66.B67.A68.B69.C70.D71.B72.A73.B74.C75.D76.B77.D78.C79.A80.A