Question

Daca x supra y= 3 supra 5, y≠0, atunci 4x+6y supra x+y= ?

Daca x supra 4= y supra 7, atunci 9x-2y supra x+3y= ?

Daca x supra 2= y supra 9, atunci 10x-2y supra 5x+y= ?

Answer 1

x/y=3/5 ⇒ x=3y/5
(4x+6y)/(x+y)= (4×3y/5 + 6y)/(3y/5 + y)
                   =(12y+30y)/5 × 5/(3y+5y)
                   =42y/8y
                   =21/4
x/4=y/7 ⇒ x=4y/7
(9x-2y)/(x+3y)= (9×4y/7 - 2y)/(4y/7 +3y)
                     =(36y-14y)/7 × (7/4y+21y)
                     =22y/25y
                     =22/25
x/2=y/9 ⇒ x=2y/9
(10x-2y)/(5x+y)= (10×2y/9 -2y)/(5×2y/9 +y)
                      = (20y-18y)/9 ×9/(10y+9y)
                     =2y/19y
                     =2/19