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19 votes
What is the solution to the equation below?
√x-4=x-10

User Nikhil S
by
3.4k points

1 Answer

8 votes

Answer:


x=13

Explanation:

Step 1: Isolate the square root on the left hand side

Radical already isolated

√x-4 = x-10

Step 2: Eliminate the radical on the left hand side

Raise both sides to the second power

(√x-4)2 = (x-10)2

After squaring

x-4 = x2-20x+100

Step 3: Solve the quadratic equation

Rearranged equation

x2 - 21x + 104 = 0

This equation has two rational roots:

{x1, x2}={13, 8}

Step 4: Check that the first solution is correct

Original equation

√x-4 = x-10

Plug in 13 for x

√(13)-4 = (13)-10

Simplify

√9 = 3

Solution checks !!

Solution is:

x = 13

Step 5: Check that the second solution is correct

Original equation

√x-4 = x-10

Plug in 8 for x

√(8)-4 = (8)-10

Simplify

√4 = -2

Solution does not check

2 ≠ -2

One solution was found :

x = 13

User Bonkles
by
3.8k points