Factor the trinomial completely. $r ^ { 2 } - 4 r - 5$
A) $( r + 5 ) ( r + 1 )$
B) $( r - 5 ) ( r + 1 )$
C) $( r + 5 ) ( r - 1 )$
D) $( r - 5 ) ( r - 1 )$
E) not factorable

Question

Quizplus · Accepted Answer

The correct factorization of $r^2 - 4r - 5$ is found by looking for two numbers that multiply to -5 and add to -4. Those numbers are -5 and +1, leading to the factorization $(r - 5)(r + 1)$.

Factor the Trinomial Completely r2−4r−5r ^ { 2 } - 4 r - 5r2−4r−5

Factor the Trinomial Completely $r ^ { 2 } - 4 r - 5$