Answer:
x=3
Explanation:
3x-y=3 -----1
9x^2-y^2=45-----2
making x the subject of the formular in equ 1
3x=3 + y
x =(3 + y)/3
substituting x with (3 + y)/3 in equ 2
9[(3 + y)/3]^2 - y^2=45
9[(1 + y/3)]^2 - y^2=45
9[(1 + y/3)(1 + y/3)] - y^2=45
9[1 + y/3 + y/3 + y^2/9] - y^2=45
9[1 + (2y)/3 + (y^2)/9] - y^2=45
9 + 6y + y^2 - y^2=45
9 + 6y =45
6y=45-9
6y = 36
y = 36/6
y = 6
substituting y for 6 in equ 1
3x-6=3
3x=3 + 6
3x = 9
x =9/3
x=3
