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30 votes
30 votes
Solve: √2x-9 = x-6
a) x=9
b) The equation has no solution.
c) x= 5,9
d) x=5

User Katya Willard
by
2.6k points

1 Answer

17 votes
17 votes

Answer:

A

Explanation:

STEP 1:

Isolate the square root on the left hand side

Radical already isolated

√2x-9 = x-6

STEP 2:

Eliminate the radical on the left hand side

Raise both sides to the second power

(√2x-9)2 = (x-6)2

After squaring

2x-9 = x2-12x+36

STEP 3:

Solve the quadratic equation

Rearranged equation

x2 - 14x + 45 = 0

This equation has two rational roots:

{x1, x2}={9, 5}

STEP 4:

Check that the first solution is correct

Original equation

√2x-9 = x-6

Plug in 9 for x

√2•(9)-9 = (9)-6

Simplify

√9 = 3

Solution checks !!

Solution is:

x = 9

STEP 5:

Check that the second solution is correct

Original equation

√2x-9 = x-6

Plug in 5 for x

√2•(5)-9 = (5)-6

Simplify

√1 = -1

Solution does not check

1 ≠ -1

One solution was found :

x=9

Hope this helps!!

User Rigel Glen
by
3.0k points