How do you solve sqrt(3x-2)=1+sqrt(2x-3)?

2 Answers
Sep 29, 2016

x = 2 and 6

Explanation:

Given:" "sqrt(3x-2)=1+sqrt(2x-3)

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Square both sides

3x-2" "=" "1+2sqrt(2x-3)+2x-3

The -2 on both sides cancel out

3xcancel(-2)" "=" "2xcancel(-2)+2sqrt(2x-3)

3x=2x+2sqrt(2x-3)

Subtract 2x from both sides

x=2sqrt(2x-3)

Divide both sides by 2

x/2=sqrt(2x-3)

Square both sides

x^2/4 =2x-3

giving:" "x^2/4-2x+3=0

Using the standardised formula y=ax^2+bx+c

a=1/4"; "b=-2"; "c=3

where x=(-b+-sqrt(b^2-4ac))/(2a)

=> x= (+2+-sqrt((-2)^2-4(1/4)(3)))/(2(1/4))

=> x=4 +-(sqrt(4-12/4))/(1/2)

x=4+- 2

color(brown)(x=2" and "x=6

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
color(blue)("However:")

Consider sqrt(2x-3)

For x in RR: 2x>=3 otherwise 2x-3 is negative

color(brown)(=>x>=3/2)

,..............................................................................................
Consider sqrt(3x-2)

For x in RR: 3x>=2 otherwise 3x-2 is negative

color(brown)(=> x>=2/3)
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color(blue)("Putting it all together")

color(brown)("If "x<3/2" then at least one of the roots is negative")

color(brown)("As both "x=2" and "x=6" are greater than "3/2)color(brown)("both are feasible solutions")

" "color(green)(bar(ul(|color(white)(2/2)x=2" and "x=6" "|))
Tony BTony B

Sep 29, 2016

color(green)(x=2color(black" or ")x=6)

Explanation:

Given
color(white)("XXX")sqrt(3x-2)=1+sqrt(2x-3)

Square both sides
color(white)("XXX")3x-2=1+2sqrt(2x-3)+2x-3

Simplify
color(white)("XXX")3x-2=2sqrt(2x-3)+2x-2

Isolate the term with the root on one side
color(white)("XXX")x= 2sqrt(2x-3)

Square both sides
color(white)("XXX")x^2 = 8x-12

Convert to standard form
color(white)("XXX")x^2-8x+12=0

Factor to get
color(white)("XXX")(x-2)(x-6)=0

rArr x=2 or x=6