Cho `x= 1`
`=> A(1) = 12. 1^3 + 2a.1 +a^2`
`=> A(1) = 12 + 2a + a^2`
Cho `x= -2`
`=> B(-2)= 2.(-2)^2 - |2a+3| .(-2) + a^2`
`=> B(-2)= 2.4 -(-2).|2a+3| + a^2`
`=> B(-2) = 8 + 2|2a+3| +a^2`
Vì `A(1) = B(-2)`
`=> 12 + 2a + a^2 = 8 + 2|2a+3| + a^2`
`=> 12 -8 + 2a + a^2 - a^2 = 2|2a+3|`
`=> 4 + 2a = 2|2a+3|`
`=> (4+2a):2 = |2a+3|`
`=> 2 + a = |2a+3|`
+) `2a + 3= 2 +a`
`=> 2a - a = 2-3`
`=> a = -1`
+) `2a + 3= -2 - a`
`=> 2a +a = -2 -3`
`=> 3a = -5`
`=> a= -5/3`
Vậy `a= -1` hoặc `a= -5/3`
