Question

if 4x - 3y = 4 and xy=1 , find the value of 4x+3y
if you give correct answer I will mark you brainlist ​

Answer 1

Answer:

8 and -8

Step-by-step explanation:

We first need to find the values of 'x' and 'y'

xy=1 or x=1/y

input x in 1st eq

4(1/y)-3y=4

Taking L.C.M

4/y-3y²/y=4

4-3y²=4y

0=3y²+4y-4

0=3y²+6y-2y-4

0=3y(y+2)-2(y+2)

0=(3y-2)(y+2)

So y=2/3 or y=-2

now use this value and find x

x=1/y or 3/2 or -1/2

now when x and y are 3/2 and 2/3

4(3/2)+3(2/3) = 6+2 = 8

now when x and y are -1/2 and -2

4(-1/2)+3(-2) = -2-6 = -8

Hope this helps.

Answer 2

xy=1

x=1/y

now x=1/y put in equation

4x1/y-3y=4

4/y-3y=4

both termes multiply by 'y'

4/y x y-3y x y=4xy

4-3y2=4y

4-3y2-4y=0

3y2-4y+4=0

3y2-6y+2y-4=0

3y(y-2)+2(y-2)=0

(y-2)(3y+2)=0

so, y=-2/3 or y=2

now case ( 1 )

x=2/y

y=-2/3 put in

x=2/-2/3

x=-3.33

now ,

4x+3y

put value's of x & y

4x-3.33+ 3 x-2/3

=-13.32-1.98

= -15.3

now case (2)

x=2/y

y=2 put in

x=2/2

x=1

put value's of x & y

4x+3y

=4x1+3x2

=4+6

=10