Question

If the sum and product of two numbers are respectively 40 and 375, then their difference is

• A. 15
• B. 13
• C. 10
• D. 16

Answer 1

Answer:

C. 10

Let one number be X, then the other number is 40 - X

$X(40-X)=375$

$40X-X^2=375$

$X^2-40X=-375$

Add square of the half of the coefficient of X to both side

$X^2-40X+400=25$

$(X-20)^2=25$

$X-20=\sqrt{25}$

$X-20=5$

$X=20+5=25$

one number is 25 and the other number is 40 -25 = 15

The difference between the numbers = 25 - 15 = 10