1.若方程组ax-by=4 ax+by=2与2x+3y=9 4x-5y=7同解,则a=_______,b=________.

题目

1.若方程组ax-by=4 ax+by=2与2x+3y=9 4x-5y=7同解,则a=_______,b=________.
2.已知x+y+z=1,x+y+t=2,x+z+t=3,y+z+t=9,则x+y+z+t的值是_________.

答案

1.a=1,b=-1
2.5