Question

If 2y-5x=5 what is the smallest integral value of x for which y>100?

Answer 1

anyone please solve this

Answer 2

just try plugging in y=100 then solve.

Answer 3

ok, let me try

Answer 4

x=39

Answer 5

but the answer is 20

Answer 6

Let's explore and see what is REALLY going on.

2y - 5x = 5

x = (2y - 5)/5
x = (2(100) - 5)/5 = (200 - 5)/5 = 195/5 = 39

y = (5 + 5x)/2
y = (5 + 5(38))/2 = (5 + 190)/2 = 195/2 = 97.5
y = (5 + 5(39))/2 = (5 + 195)/2 = 200/2 = 100
y = (5 + 5(40))/2 = (5 + 200)/2 = 205/2 = 102.5

The correct answer, the the problem posed, is x = 40

If it had said \(y \ge 100\), the answer would be x = 39.

"20" is simply incorrect.

Answer 7

ahh thanks tkhunny