Nine times a certain number is 5 less than twice the square of the number

Question

Half Pint

Mathematics

13 September, 21:50

Nine times a certain number is 5 less than twice the square of the number

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Answers (2)

Know the Answer?

Aylin Bird · Answer 1

-1/2 or 5

Step-by-step explanation:

9n = (2 * n^2) - 5 = > n = - 0.5 and n = 5

Judith Herman · Answer 2

Step-by-step explanation:

9·x = 2·x^2 - 5

2·x^2 - 9·x - 5 = 0

x^2 - 9/2·x - 5/2 = 0

x = 9/4 ± √ (81/16 + 40/16) = 9/4 ± √ (121/16) = 9/4 ± 11/4

x1 = - 1/2 = - 0.5 or x2 = 5