Question

例:已知代数式9—6y—4y^2=7,求2y^2+3y+7的值.由9—6y—4y^2=7得—6y—4y^2=

Answer 1

解

由9-6y-4y^2=7得

-6y-4y^2=-2

6y+4y^2=2

3y+2y^2=1

所以

2y^2+3y+7

=1+7

=8