Question

Mathematicians 4: Who is Who?

Unit: Factoring Quadratics
Factor the following quadratic equations to determine each person's name: Show your work

Answer 1

a. x = -9 or x = -2

b. -5(x - 4)

c. x = -3 or x = 5

d. x = ±7

Explanation:

a. First person;

y = x² + 11x + 18

y = x² + 9x + 2x + 18

y = x(x + 9) + 2(x + 9)

y = (x + 9)(x + 2)

y = x = -9 or x = -2

b. Second person;

y = -5x + 20

The common factor is 5.

y = -5(x - 4)

c. Third person;

y = x² - 2x - 15

y = x² - 5x + 3x - 15

y = x(x - 5) + 3(x - 5)

y = (x + 3)(x - 5)

y = x = -3 or x = 5

d. Fourth person;

y = x² - 49

Applying the difference of squares formula;

(a² - b²) = (a - b)(a + b)

y = x² - 49 = x² - 7² = (x - 7)(x + 7)

y = (x - 7)(x + 7)

y = x = ±7