Question

The difference of two perfect cubes is 386. If the cube root of the smaller of the two numbers is 7, then the cube root of the larger number is​

Answer 1

Answer:

9

Step-by-step explanation:

Let the two perfect cubes be x and y where x > y.

According to the given conditions:

${x}^{3} - {y}^{3} = 386...(1) \\ y = 7...(2) \\ plug \: y = 7 \: in \: equation \: (1) \\ {x}^{3} - {7}^{3} = 386 \\ {x}^{3} - 343 = 386 \\ {x}^{3} = 343 + 386 \\ {x}^{3} = 343 + 386 \\ {x}^{3} = 729 \\ x = \sqrt[3]{729} \\ x = 9$

Thus the cube root of the larger number is 9.