Question

In the equation above. K is a constant. If x=9, what value is k? A) 1 B) 7 C) 16 D) 79

Answer 1

Answer: 79

Explanation:

`√(k+2)-9=0\\\\√(k+2)=9\\\\k+2=81\\\\k=\boxed{79}`

Answer 2

D) k = 79

Explanation:

Given equation:
`\sf√(k+2)-x=0`

Steps:

1. Substitute 9 as the value of x in the equation:

`\sf√(k+2)-9=0`

2. Add 9 to both sides:

`\sf√(k+2)-9+9=0+9\\\\\Rightarrow √(k+2)=9`

3. Square both sides of the equation:

`\sf\left(√(k+2)\right)^2=9^2\\\\\Rightarrow k+2=81`

4. Subtract 2 from both sides:

`\sf k+2-2=81-2\\\\\Rightarrow k = 79`

5. Check your work:

`\sf√(k+2)-x=0\ \textsf{[ substitute 79 for k, and 9 for x ]}\\\\√(79+2)-9=0\ \textsf{[ add ]}\\\\√(81)-9=0\ \textsf{[ take the square root ]}\\\\9-9=0\ \textsf{[ subtract ]}\\\\0=0\ \checkmark`