Question

I think of a number, multiply it by 4, add 1 and square the result

Answer 1

Answer:

Let the number be x. Adding 7 to x means (x + 7). Subtracting 2 from (x + 7), we get (x + 5). Subtracting original numbet from (x + 5) gives us (x + 5) — x = 5. Multiplying 5 by 4 gives us 5 × 4 = 20 and subtracting 2 from 20 gives us 18. Thus the result is 18.

Let x = 5. Then according to the procedures,

Step 1. 5 + 7 = 12

Step 2. 12 — 2 = 10

Step 3. 10 — 5 = 5

Now 5 × 4 = 20 and subtracting 2 from it gives us 18.

Let x = 12. Then according to the problem,

Step 1. 12 + 7 = 19

Step 2. 19 — 2 = 17

Step 3. 17 — 12 = 5

Again we got the result 5 at step 3. Hence 5×4 = 20 and 20 — 2 = 18. Thus it is true for every whole number. Does it is true for negative numbers?

Let x = —7. Then according to the problem,

Step 1. —7 + 7 = 0

Step 2. 0 — 2 = —2

Step 3. —2 — 7 = —5

Now —5 × 4 = —20 and —20 — 2 = —22, which is not equal to 18.

Answer 2

Answer:-

Let the number be x. Adding 7 to x means (x + 7). Subtracting 2 from (x + 7), we get (x + 5). Subtracting original numbet from (x + 5) gives us (x + 5) — x = 5. Multiplying 5 by 4 gives us 5 × 4 = 20 and subtracting 2 from 20 gives us 18. Thus the result is 18.

Let x = 5. Then according to the procedures,

Step 1. 5 + 7 = 12

Step 2. 12 — 2 = 10

Step 3. 10 — 5 = 5

Now 5 × 4 = 20 and subtracting 2 from it gives us 18.

Let x = 12. Then according to the problem,

Step 1. 12 + 7 = 19

Step 2. 19 — 2 = 17

Step 3. 17 — 12 = 5

Again we got the result 5 at step 3. Hence 5×4 = 20 and 20 — 2 = 18. Thus it is true for every whole number. Does it is true for negative numbers?

Let x = —7. Then according to the problem,

Step 1. —7 + 7 = 0

Step 2. 0 — 2 = —2

Step 3. —2 — 7 = —5

Now —5 × 4 = —20 and —20 — 2 = —22, which is not equal to 18.