来自孟宪奇的问题
已知3a-5b+19=0,a+8b-1=0.求下列各式的值:1:-12a-9b2:4a-26b
已知3a-5b+19=0,a+8b-1=0.求下列各式的值:
1:-12a-9b2:4a-26b
1回答
2020-03-26 23:28
已知3a-5b+19=0,a+8b-1=0.求下列各式的值:1:-12a-9b2:4a-26b
已知3a-5b+19=0,a+8b-1=0.求下列各式的值:
1:-12a-9b2:4a-26b
小状元AAA:
3a-5b+19=0,3a-5b=-19①
a+8b-1=0,即a+8b=1②
①+②,得
4a+3b=-18
①-②,得
2a-13b=-20
1、-12a-9b
=-3(4a+3b)
=-3×(-18)
=54
2、4a-26b
=2(2a-13b)
=2×(-20)
=-40