Question 1 (1) Substitute y=2x-7 into 5x+3y+2z=2 to get 1 1x+2z=23, multiply by 2 to get 22x+4z=46, and add it to 3x-4z=4 to get x =

(2)3y-2z = 1 times 3 to get 9y-6z = 3；; 4x+9y= 12 minus 9y-6z=3 to get 4x+6z = 9；; 4x+6z=9 times 7 to get 28x+42z=63, 7x+5z= 19/4 times 4 to get 28x+20z =19; The sum of the two formulas gives 22z=44, and the solution gives z=2. Substituting them into the solution, X =-3/4 and Y = 5/3 are obtained respectively.