Question

If the X + Y = 12 and xy = 7 find the value of x and y

Answer 1

Given, X + Y = 12 .........(1)
and XY = 7 ..........(2)

from equation (1),
Y = 12 - X , put it in equation (2),

X(12 - X) = 7

12X - X² = 7

X² - 12X + 7 = 0

use quadratic formula,
X = {12 ± √(12² - 4 × 7)}/2

X = {12 ± √(144 - 28)}/2

X = 6 ± √29

hence, X = 6 ± √29

and Y = 12 - (6 ± √29) = $(6\mp\sqrt{29})$

Answer 2

Answer:

3 and 4

u need to solve it graphically