Question

7x +3y =15;12y-5x =39 by simultaneous equation

Answer 1

Answer:

X=21/33 and y = 116/33

Step-by-step explanation:

3y=15-7x

y=(15-7x)/3.......1

Plug 1 in eq 2

12((15-7x)/3)-5x=39

4(15-7x)-5x=39

60-28x-5x=39

60-39=33x

21/33=X......2

Plug 2 in 1

y=15-7(21/33)/3

y=5-49/33

y=(165-49)/33

y=116/33

Answer 2

Answer:

7x+3y=15--------------(1)

12y-5x=39

:•-5x+12y=39-----------(2)

multiply eq (1) by 4

=28x+12y=60-----------(3)

sub eq (2) from (3)

Step-by-step explanation:

28x+12y=60

-5x+12y=39

+ - +

--------------------------

12y 12y gets cut

33x=21

x=21/33= x=7/11

put x=7/11 in eq (1)

7(7/11)+39=15

49/11+39=15

multiply by 11

11×49/11+11×39=11×15

49+33y=165

33y=165-49

33y=116

therefore y=116/3

(x,y)=(7upon 11 and 116 upon 3)