Remove the brackets from (x-4) - (- y + 2Z)______ [urgent]

Remove the brackets from (x-4) - (- y + 2Z)______ [urgent]

(x-4)-(-y+2z)
=x-4+y-2z

A = {x vertical line X & # 178; + 4x = 0} B = {x vertical line X & # 178; + 2 (a + b) x + A & # 178; - 1 = 0} if AUB = B, find the value of a; if a ∩ B = B, find the value of A
If B = empty set

A={0,-4}
A∩B=B
one
B is an empty set! Satisfy! Then the equation x & # 178; + 2 (a + 1) x + A & # 178; - 1 = 0 (is there a missing x?) discriminant - 1!)
From the above discussion: a

What is the meaning of the vertical line after r in {x ∈ R | X & # 178; + 1 = 0}?

The front of the vertical line indicates what the elements of the set are. Here is the number x, and X belongs to the range of real numbers
After the vertical line, the condition that x satisfies is given, that is, the equation x & # 178; + 1 = 0
Vertical bars are used to separate set elements from conditions
If you don't understand, ask. If you understand, please accept!

​ (X & # 178; + ax + 3) (X & # 178; - ax + 3) = the fourth power of X + 2x & # 178; + 9
Find a

Because [(X & # 178; + 3) + ax] [(X & # 178; + 3) - ax] = (X & # 178; + 3) & # 178; - (AX) & # 178; the original equation can be reduced to: (X & # 178; + 3) & # 178; - (AX) & # 178; = x ^ 4 + 2x & # 178; + 9, moving to merge: (4-A & # 178;) x & # 178; = 0, so: 4-A & # 178; = 0, so: a = - 2 or 2