Question

If a-b=7and ab =18; find a-b.

Answer 1

Answer:

Step-by-step explanation:

a - b = 7 .........1

ab = 18 ..........2

From eqn. 1,

a = 7 + b

Substitute this in eqn. 2

(7 + b)b = 18

b² + 7b = 18

b² + 7b - 18 = 0

b² - 2b + 9b - 18 = 0

b(b - 2) +9(b - 2) = 0

(b - 2)(b + 9) = 0

(b - 2) = 0

b = 2

(b + 9) = 0

b = -9

When b = 2

a = 7 + b

a = 7 + (2)

a = 9

When b = -9

a = 7 + b

a = 7 + (-9)

a = -2

a - b = 7