Question

if a+b=7 and ab=10 find a-b

Answer 1

a + b = 7 a= 7 - b

ab = 10
(7-b)b = 10
7b - b² = 10
b² - 7b + 10 = 0
b² - 5b - 2b + 10 = 0
b( b - 5 ) - 2(b-5) = 0
b = 2 , b = 5


when b = 2 , a = 5
therefore , a - b = 5 -2 = 3
and when b = 5 , a = 2
a- b = 2-5 = -3