Question

The sum of a number and its square is 42. Which equation can be used to find the two numbers for which this is true?

x2 + 2x = 42

x2 + x = 42

x2 + 2x + 42 = 0

x2 + x + 42 = 0

Answer 1

x²+x=42 ( the number is either 6 or -7)

Explanation:

x²+x=42

x²+x-42=0

x² +7x-6x-42=0 (midterm break)

x(x+7)-6(x+7)=0

(x-6)(x+7)=0

x-6=0; x+7=0

x=6; x=-7