X2+3x-4 please do this question ASAP

The multiplication property of zero states that the product of any number and 0 is 0. what must be true about either a or b to make ab=0

Asporting good store is offering 30 percent off of the original price(x) of football cleats. the discount will be reduced by an another $7 before sales tax.

What are the solutions of the following system? y=-2x^2 y=x-2