Question

1.已知a+b=3,求a的平方-b的平方+6b的值 2.已知（x+y）的平方=25,求（2x+2y-1）（2x+2y+1

Answer 1

1.已知a+b=3,求a的平方-b的平方+6b的值

a²-b²+6b

=(a+b)(a-b)+6b

=3(a-b)+6b

=3(a+b)

=9

2.已知（x+y）的平方=25,求（2x+2y-1）（2x+2y+1）的值

(2x+2y-1)(2x+2y+1)

=4(x+y)²-1

=100-1

=99