If a point is an extreme point of a binary function, then this point () A: It must be a differentiable point of a function B: It must be an undifferentiable point of a function C: It must be the stationary point of the function D: Or stationary point or nondifferentiable point

If a point is an extreme point of a binary function, then this point () A: It must be a differentiable point of a function B: It must be an undifferentiable point of a function C: It must be the stationary point of the function D: Or stationary point or nondifferentiable point

This is a concept problem. I suggest you take a good look at the definition of extreme value point of binary function

If a + B = 1, a + 3B = - 1, then the solution of (a + 2b) x-by = 6AX + (2a-b) y = 6 is___ ．

A + B = 1, ① a + 3B = - 1, ②, ① - ②: - 2b = 2, that is, B = - 1, substituting B = - 1 into ① to get: a = 2, substituting a = 2, B = - 1 into the equations to get: y = 62x + 5Y = 6, the solution is: x = - 12Y = 6. So the answer is: x = - 12Y = 6

If a + B = 1, 2A + 3B = 1, the system of equations (a + 2b) x-6y = 6 ax + (2a-b) y = 6 is solved

a+b=1 2a+3b=1
a+2b=0
b=-1,a=2
2a-b=5
（a+2b）x-6y=6 ax+（2a-b）y=6
-6y=12x+5y=6
-6y=6
12x+5y=6
y=-1,x=11/12