If X-Y = - 3, find the value of 2 / 2 x + y-xy

If X-Y = - 3, find the value of 2 / 2 x + y-xy

If X-Y = - 3, then:
2 / 2 (x + y) - XY
=2 / 2 (x square + y square - 2XY)
=2 / 2 (X-Y) square
=9 / 2

(y+1)2-2(y+1)=3 ; {x+y=4{xy=5 ; {x2+x-2y+4=0{2x-y+1=0
Solve equation 3

(1) Taking y + 1 as a whole factorization, we can get (y + 2) (Y-2) = 0. Then y = 2 or y = - 2
(2) Let x + y square be x ^ 2 + y ^ 2 = 6, and let xy = 5 be (X-Y) ^ 2 = - 4, so there is no solution
(3) If the two equations are combined to get x ^ 2 + x-4x-2 + 4 = 0, we can deduce x = 2 or 1 and substitute 2x-y + 1 = 0 to get x = 2, y = 5 or x = 1, y = 3

If # is a new operation symbol, let x # y = x + y, then in - 2 # M = 8, find the value of M

Strictly speaking, this question can have two answers, because the questions are incomplete and there is no priority for # and -
Priority is what kind of operation should be carried out first when there are no brackets. The operation of the same priority should be carried out from left to right, and the operation of different priorities should be carried out first
For example, the priority of multiplication and division is 1-2 × 3 = 1 - (2 × 3) = - 5 and not equal to (1-2) × 3
Similarly, if the priority of specified operation is higher than that of subtraction, the answer is - 10
On the contrary, the answer is 10
Do not rigidly stick to the answer, strictly up, many of the middle school questions are problematic, understand the truth is the most important! I wish you a happy study!