Question

当x=2时，代数式ax的立方-bx+1的值等于-17，那么当x=-1时，代数式12ax-3bx的立方-5的值等于？

Answer 1

值=22
ax的立方-bx+1的值等于-17
代入得
8a-2b+1=-17==>2(4a-b)=-18==>4a-b=-9
当x=-1时，求代数式的12ax-3bx的立方-5
-12a+3b-5=-3(4a-b)-5=-3*-9-5=27-5=22

Answer 2

a * (2)^3 - b * 2 +1 = -17 ==> 8a - 2b = -18 ==> 4a - b = -9 12a * (-1) - 3b * (-1)^3 - 5 = -12a +3b - 5 = -3(4a - b) - 5 = -3 * (-9) - 5 = 22