Question

If the sum and product of two numbers are respectively 40 and 375, then find the numbers

• A. 20, 20
• B. 30, 10
• C. 25, 15
• D. 35, 5

Answer 1

Answer:

C. 25, 15

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