Question

Pls help w this

√2x+1 = 4
In the equation above, what is the value of 2x +1?
A) 3/2
B) 2
C) 4
D) 16

Answer 1

D :) because you have to square both sides of the equation to get the 2x+1 by itself which would equal 16

Answer 2

`\boxed {\boxed {\sf D. \ 16}}`

Explanation:

We are given the following equation and asked to solve for 2x+1.

`\sqrt {2x+1}=4`

We want to isolate the entire expression of 2x+1. Notice that it is under the square root. If we want to isolate it, we have to perform the inverse operation. The inverse of a square root is a square, so we square both sides of the equation.

`(√(2x+1) )^2= (4)^2`

`2x+1=(4)^2`

`2x+1=16`

We could continue solving for x, then plug the answer back into the expression 2x+1. However, hopefully you notice that we already found the answer!

We only had to do one step to find the answer, but you could complete many other steps to get the same answer:

`2x+1-1=16-1\\2x=15\\2x/2=15/2\\x= 7.5` (Solve for x)

`2x+1\\2(7.5)+1\\15+1\\16` (Plug the answer in for x)

The value of 2x+1 is 16 and the correct answer is 16.