Question

高一交集练习题求教已知集合A={y|y=x²-2ax+3b},B={y|y=-x²-2ax+7b},且A∩B={y|2≤

Answer 1

y=x²-2ax+3b=y=x²-2ax+a^2+3b-a^2

=(x-a)^2+(3b-a^2) y>=3b-a^2

y=-x²-2ax+7b=-x²-2ax-a^2+7b+a^2

=-(x+a)^2+(7b+a^2) y