find the zeroes of the quadratic polynomial x2-20x+120
Answers
1.1 Factoring x2-20x-120
The first term is, x2 its coefficient is 1 .
The middle term is, -20x its coefficient is -20 .
The last term, "the constant", is -120
Step-1 : Multiply the coefficient of the first term by the constant 1 • -120 = -120
Step-2 : Find two factors of -120 whose sum equals the coefficient of the middle term, which is -20 .
-120 + 1 = -119
-60 + 2 = -58
-40 + 3 = -37
-30 + 4 = -26
-24 + 5 = -19
-20 + 6 = -14
-15 + 8 = -7
-12 + 10 = -2
-10 + 12 = 2
-8 + 15 = 7
-6 + 20 = 14
-5 + 24 = 19
-4 + 30 = 26
-3 + 40 = 37
-2 + 60 = 58
-1 + 120 = 119
Observation : No two such factors can be found !!