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Subject Test Math 1

Question 4 of 32

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SAT Subject Test

A number n is increased by 8. If the cube root of that result equalsnegative 0.5, what is the
value of n invisible times ?

Select an Answer

negative 15.625

Correct Answer: 
No

negative 8.794

Correct Answer: 
No

negative 8.125

Correct Answer: 
Yes

negative 7.875

Correct Answer: 
No

421.875

Correct Answer: 
No

The correct answer is C.

One way to determine the value of n is to create and solve an algebraic equation. The phrase “a number n is increased by 8” is represented by the expression n plus 8, and the cube root of that result is equal to negative 0.5, so root index 3 of n plus 8 end root equals negative 0.5 invisible times. Solving for n gives n plus 8 equals left parenthesis negative 0.5 right parenthesis to the power of 3 end exponent equals negative 0.125, and so n equals negative 0.125 minus 8 equals negative 8.125.

Alternatively, one can invert the operations that were done to n. Apply the inverse of each operation, in the reverse order: First cube negative 0.5 to get negative 0.125, and then decrease this value by 8 to find that n equals negative 0.125 minus 8 equals negative 8.125.

Question Difficulty: 
easy