Solve 5x2 - 7x + 2 = 0 by completing the square.
What is the constant added on to form the perfect square trinomial?
49/4
49/25
49/100
5x^2 - 7x + 2 = 0
5x^2 - 7x = - 2 factor out 5
5 (x^2 - (7/5)x ) = -2 take (1/2) of (7/5) = 7/10....square it = 49/100...add and subract it within the parentheses
5 ( x^2 - (7/5)x + 49/100 - 49/100) = -2 divide both sides by 5
x^2 - (7/5)x + 49/100 - 49/100 = - 2/5 add 49/100 to both sides
x^2 - (7/5)x + 49/100 = -2/5 + 49/100 factor the left side
(x - 7/10)^2 = -40/100 + 49/100
(x - 7/10^2 = 9/100 take both roots
x -7 /10 = ±√ (9/100)
x - 7/10 = ±3/10 add 7/10 to both sides
x = ±3/10 + 7/10
x = 3/10 + 7/10 = 1 or x = -3/10 + 7/10 = 4/10 = 2/5
49/100 is the added constant