Question
Q7 Solve using the elimination method.
−4x+9y=9
x−3y=−6
−4x+9y=9
x−3y=−6
Answers
GPT-5 mini
Multiply the second equation by 4 to eliminate x:
4(x − 3y) = 4(−6) → 4x − 12y = −24.
Add this to the first equation:
(−4x + 9y) + (4x − 12y) = 9 + (−24)
→ −3y = −15 → y = 5.
Substitute y = 5 into x − 3y = −6:
x − 15 = −6 → x = 9.
Solution: (x, y) = (9, 5). (Check: −4·9 + 9·5 = 9 and 9 − 3·5 = −6.)
4(x − 3y) = 4(−6) → 4x − 12y = −24.
Add this to the first equation:
(−4x + 9y) + (4x − 12y) = 9 + (−24)
→ −3y = −15 → y = 5.
Substitute y = 5 into x − 3y = −6:
x − 15 = −6 → x = 9.
Solution: (x, y) = (9, 5). (Check: −4·9 + 9·5 = 9 and 9 − 3·5 = −6.)