若有理数a、b、c在数轴上的位置如图所示:
且d=|a+b|-|-2-b|-|a-2c|-5,求
7(d+2c)2+2(d+2c)-5(d+2c)2-3(d+2c)的值.
由已知有:a+b<0,-2-b>0,a-2c<0
∴d=-a-b+2+b+a-2c-5
=-3-2c
∴d+2c=-3
7(d+2c)2+2(d+2c)-5(d+2c)2-3(d+2c)
=2(d+2c)2-(d+2c)
=2×(-3)2-(-3)
=2×9+3
=18+3
=21
不知道对不对= =
若有理数a、b、c在数轴上的位置如图所示:
且d=|a+b|-|-2-b|-|a-2c|-5,求
7(d+2c)2+2(d+2c)-5(d+2c)2-3(d+2c)的值.
由已知有:a+b<0,-2-b>0,a-2c<0
∴d=-a-b+2+b+a-2c-5
=-3-2c
∴d+2c=-3
7(d+2c)2+2(d+2c)-5(d+2c)2-3(d+2c)
=2(d+2c)2-(d+2c)
=2×(-3)2-(-3)
=2×9+3
=18+3
=21
不知道对不对= =