2S+3T-1=0 4S-9T-8=0 求ST……
问题描述：
2S+3T-1=0 4S-9T-8=0 求ST……
答
2S+3T-1=0---------(1)
4S-9T-8=0--------(2)
(1)*2-(2)得
15T+6=0
T=-2/5=-0.4
S=11/5=2.2
答
10S-11=0
15T+6=0
ST=11/10*(-6)/15
=-0.44
答
2S+3T-1=0.(1)
4S-9T-8=0.(2)
(1)*2-(2),得
15T+6=0
15T=-6
T=-0.4
代入(1),得
2S+3*(-0.4)-1=0
2S-1.2-1=0
2S=2.2
S=1.1
所以
S=1.1,T=-0.4