Question

At what corridnate point do y= 1/2 x + 4 and x + 4y = 4 intersect.

Answer 1

(-4;2)

Explanation:

1. if y=1/2 x+4, then 2y=x+8; it is possible to re-write as x-2y+8=0;

2. if x+4y=4, it is possible to re-write it as x+4y-4=0;

3. if x-2y+8=0 and x+4y-4=0, then x-2y+8=x+4y-4; ⇒ -2y+8=4y-4; ⇒ 6y=12; ⇔ y=2.

4. if y=2, then it is possible to substitute its value into any equation given in the condition:

x+4y=4 (substitution y=2); ⇒ x+8=4; ⇒ x= -4.

5. finally x= -4; y=2. It means (-4;2)

PS. the suggested solution is not the only way to resolve this task.