a. B, C and D are four rational numbers whose absolute values are 1, 2, 3 and 4 respectively (1) Please write two formulas so that a + B + C + D = - 2 Formula 1:_____________ Formula 2:_____________ (2) Can you write a formula so that a + B + C + D = - 1:1______ (fill in "can" or "can't")

a. B, C and D are four rational numbers whose absolute values are 1, 2, 3 and 4 respectively (1) Please write two formulas so that a + B + C + D = - 2 Formula 1:_____________ Formula 2:_____________ (2) Can you write a formula so that a + B + C + D = - 1:1______ (fill in "can" or "can't")

(1)1-2+3-4
-1-2-3+4
(2) No, because no matter how the four numbers are added or subtracted, the result is always even and cannot be - 1