Question

已知A=3a^2-2b^2,B=a^2+6b^2,若A=5,B=15,求a^2-a^2b^2+4b^2的值

Answer 1

A=5,B=15

∴3a^2-2b^2=5

a^2+6b^2=15

9a^2-6b^2=15

上下相加得

10a^2=30

a^2=3

∴b^2=2

a^2-a^2b^2+4b^2

=3-3×2+4×2

=3-6+8

=5