Question

Which of the following is a solution of 4x + 5y ≤ 20?

A. (5, 7)
B. (1, 1)
C. (0, 5)
D. (8, 0)

Answer 1

B.

Explanation:

Plug in and see:

Let's try the first (x,y)=(5,7)

4(5)+5(7) <=20

20+35<=20 not true so not A

Let's try (1,1) for (x,y)

4(1)+5(1)<=20

4+5<=20 that is true so choice B looks good

Answer 2

For this case we must replace each of the points and verify if the inequality is met:

Point: (5,7)

`4 (5) +5 (7) \leq20\\20 + 35 \leq20`

It is not fulfilled!

Point: (1,1)

`4 (1) +5 (1) \leq20\\9 \leq20`

Is fulfilled!

Point: (0,5)

`4 (0) +5 (5) \leq20\\0 + 25 \leq20`

It is not fulfilled!

Point: (8,0)

`4 (8) +5 (0) \leq20\\32 \leq20`

It is not fulfilled!

Answer:

(1,1)