If 5x + x² > 100, then x is not?

Question

10,8,7, or 9

Answer 1

5x + x² > 100

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5(10) + (10)² = 50 + 100 = 150, which is greater than 100.

5(9) + (9)² = 45 + 81 = 126, which is greater than 100.

5(8) + (8)² = 40 + 64 = 104, which is greater than 100.

5(7) + (7)² = 35 + 49 = 84, which is less than 100.

Therefore, the answer is 7.

Answer 2

5x + x² > 100

plug in the numbers

10

50+100

8

40+64

7

35+49

x is not 7

Answer 3

just plug and chug ...

if x = 10, then 5x + x^2 = 150 .... which is >100, so that's still true

if x = 8, then 5x + x^2 = 40+64 = 104, which is also true.

therefore 9 would also have to be true.

it's not 7 by process of elimination or you can calculate it and see it = 84 which is less than 100

Answer 4

7