O quadrado menos o dobro de um número é igual a -1 calcule esse número

A20? -foot ladder is placed against a vertical wall of a? building, with the bottom of the ladder standing on level ground 19 feet from the base of the building. how high up the wall does the ladder? reach?

Multiplying an even number of negative numbers gives an answer that is choose from:

Complete the statements about the system of linear equation respresented by the tables the equation respented the left table is