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Source: 2022 AMC 10B Problem 18

November 17, 2022
algebralinear equationAMCAMC 102022 AMC2022 AMC 10Bsystem of equations

Problem Statement

Consider systems of three linear equations with unknowns x,x, y,y, and z,z, \begin{align*} a_1 x + b_1 y + c_1 z = 0 \\ a_2 x + b_2 y + c_2 z = 0 \\ a_3 x + b_3 y + c_3 z = 0 \end{align*} where each of the coefficients is either 00 or 11 and the system has a solution other than x=y=z=0.x = y = z = 0. For example, one such system is {1x+1y+0z=0,0x+1y+1z=0,0x+0y+0z=0}\{1x + 1y + 0z = 0, 0x + 1y + 1z = 0, 0x + 0y + 0z = 0\} with a nonzero solution of {x,y,z}={1,1,1}.\{x, y, z\} = \{1, -1, 1\}. How many such systems are there? (The equations in a system need not be distinct, and two systems containing the same equations in a different order are considered different.)
<spanclass=latexbold>(A)</span>302<spanclass=latexbold>(B)</span>338<spanclass=latexbold>(C)</span>340<spanclass=latexbold>(D)</span>343<spanclass=latexbold>(E)</span>344<span class='latex-bold'>(A) </span> 302 \qquad <span class='latex-bold'>(B) </span> 338 \qquad <span class='latex-bold'>(C) </span> 340 \qquad <span class='latex-bold'>(D) </span> 343 \qquad <span class='latex-bold'>(E) </span> 344