Question

Fernando evaluated the expression below. StartFraction 5 (9 minus 5) over 2 EndFraction + (negative 2) (negative 5) + (negative 3) squared = StartFraction 5 (4) over 2 EndFraction minus 10 + 9 = StartFraction 20 over 2 EndFraction minus 10 + 9 = 10 minus 10 + 9 = 9. What was Fernando's error?

Answer 1

Fernando incorrectly found the product of –2 and –5.

Explanation:

Fernando evaluated the numerator of the fraction incorrectly.

Fernando simplified StartFraction 20 over 2 EndFraction incorrectly.

Fernando incorrectly found the product of –2 and –5.

Fernando evaluated (negative 3) squared incorrectly.

Fernando's calculation

5(9-5) / 2 + (-2)(-5) + (-3)^2

= 5(4) / 2 - 10 + 9

= 20/2 - 10 + 9

= 10 - 10 + 9

= 9

Correct calculation

5(9-5) / 2 + (-2)(-5) + (-3)^2

= 5(4) / 2 + (10) + 9

= 20/2 + 10 + 9

= 10 + 10 + 9

= 29

Therefore,

Fernando's error was multiplying (-2)(-5) to be equal to -10 instead of 10

Fernando incorrectly found the product of –2 and –5.