Question 418913
"what number and its square differ by 20?"


x = the number


x^2 - x = 20 {what number(x) and its square(x^2) differ by 20}
x^2 - x - 20 = 0 {subtracted 20 from both sides}
(x - 5)(x + 4) = 0 {factored into two binomials}
x - 5 = 0 or x + 4 = 0 {set each factor equal to 0}
x = 5 or x = -4 {solved each equation for x}


The number could be 5 or -4
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