Question

(28)Rewrite the equation so that y is a function of x: 7x+y=13

(29) Rewrite the equation so that y is a function of x:
3x+5y=15

Use the results in question #28 to find y when x =-1

Use the results from question #29 to find y when x=-1

Answer 1

These are two questions.

28) 7x + y = 13 => y = 13 - 7x

When x = -1, y = 13 - 7(-1) = 13 + 7 = 20.

29) 3x + 5y = 15 => 5y = 15 - 3x

=> y = [15 - 3x] / 5

When x = - 1, y = [15 - 3(-1) ] / 5 = [15 + 3] / 5 = 18/5