Anna and Belle are asked to solve - 2x - 15 = 6x + 9. Identify where one of them made an error. Anna Belle - 2x - 15 = 6x + 9 - 2x - 15 - 6x = 6x + 9 - 6x - 8x - 15 = 9 - 8x - 15 + 15 = 9 + 15 - 8x = 24 Negative 8x over negative 8 equals 24 over negative 8 x = - 3 - 2x - 15 = 6x + 9 - 2x - 15 + 2x = 6x + 9 + 2x - 15 = 8x + 9 - 15 + 9 = 8x + 9 + 9 - 6 = 8x Negative 6x over 8 equals 8x over 8 Negative two-thirds

Question

Mathematics

Ian Gilmore

15 May, 14:20

Anna and Belle are asked to solve - 2x - 15 = 6x + 9. Identify where one of them made an error. Anna Belle - 2x - 15 = 6x + 9 - 2x - 15 - 6x = 6x + 9 - 6x - 8x - 15 = 9 - 8x - 15 + 15 = 9 + 15 - 8x = 24 Negative 8x over negative 8 equals 24 over negative 8 x = - 3 - 2x - 15 = 6x + 9 - 2x - 15 + 2x = 6x + 9 + 2x - 15 = 8x + 9 - 15 + 9 = 8x + 9 + 9 - 6 = 8x Negative 6x over 8 equals 8x over 8 Negative two-thirds

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Answers (1)

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Silly Sally · Answer 1

Belle was the one who've made a mistake.

-2x-15=6x+9

-2x-15=6x+9

-6x - 6x (subtract negative 6x on the positive 6x and on negative 2x)

-8x-15=9

+15+15 (add 15 on the negative 15 and on 9)

-8x=24

-8x/-8=24/-8 (divide negative 8 on both sides)

x = - 3 (Your answer is negative 3 after dividing negative 8)

Therefore, belle was wrong