Expression problem

Solve for xx:

(x27x+12)x23x+2=1 \large \displaystyle{(x^2-7x+12)^{x^2-3x+2} = 1}

#Algebra

Note by A Former Brilliant Member
5 years, 3 months ago

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Comments

Split into three cases

Case 1: x27x+12=1x^2-7x+12 = 1, and x23x+2x^2-3x+2 is any real number

The first case will give x=7±52\displaystyle x = \frac{7\pm\sqrt{5}}{2}, which, when substitute to x23x+2x^2-3x+2, gives the exponent of 5±55\pm\sqrt{5}, which is valid, as 15±5=11^{5\pm\sqrt{5}} = 1, hence one of the answers is x=7±52\displaystyle x = \frac{7\pm\sqrt{5}}{2}


Case 2: x27x+12x^2-7x+12 is nonzero real number, and x23x+2=0x^2-3x+2=0

This will give x=1,2x = 1, 2, and it is valid as 60=20=16^0 = 2^0 = 1.


Case 3: x27x+12=1x^2-7x+12 = -1, and x23x+2x^2-3x+2 is even numbers

This will give x=7±3i2\displaystyle x = \frac{7\pm\sqrt{3}i}{2} (where i=1i = \sqrt{-1}), and the exponents is 3±3i3\pm\sqrt{3}i. It will be (1)3±3i(-1)^{3\pm\sqrt{3}i}, which gives a result in transcendental number and never equals 1


Therefore, there are four solutions, which is 1,2,ϕ+3,4ϕ1, 2, \phi+3, 4-\phi (where ϕ=1+52\displaystyle \phi = \frac{1+\sqrt{5}}{2})

Kay Xspre - 5 years, 3 months ago

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Pretty sure you meant even in the third case.

Vishnu Bhagyanath - 5 years, 3 months ago

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Yes, I wrote that incorrectly. Thanks.

Kay Xspre - 5 years, 3 months ago

Use factoring algebra. Like this : (x^2 -7x + 12) x^2-3x +2 = 1 (x-3) (x-4) (x-1) (x-2) (x=3 x=4 ) (x=1 x=2) Try to apply one by one the value of x in the algebra problems

Anggun Lestari - 5 years, 3 months ago

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You mean: (x27x+12)x23x+2=1 (x^2 -7x + 12) x^2-3x +2 = 1 (x3)(x4)(x1)(x2)(x-3) (x-4) (x-1) (x-2) x=3x=4x=3 x=4 x=1x=2x=1 x=2 ?

A Former Brilliant Member - 5 years, 3 months ago

1

Saksham Srivastava - 5 years, 3 months ago

x^2-3x+2=0 => x^2-2x-x+2 =0 x= 2, x=1

Arnob Roy - 5 years, 3 months ago
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