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How many distinct positive integer-valued solutions exist to the equation (x2−7x+11)(x2−13x+42)=1?\left(x^{2}-7 x+11\right)^{\left(x^{2}-13 x+42\right)}=1 ?

Solution

✅ Correct Option: 2

When does ab=1a^b = 1? There are exactly three situations:

The base equals 1: a=1a = 1 (exponent can be anything)

The base equals -1 and the exponent is even: a=−1a = -1 and bb is even

The exponent equals 0: b=0b = 0 (base cannot be 0)

Let's apply this to our equation: (x2−7x+11)(x2−13x+42)=1(x^2 - 7x + 11)^{(x^2 - 13x + 42)} = 1


We set the base equal to 1:

x2−7x+11=1x^2 - 7x + 11 = 1

x2−7x+10=0x^2 - 7x + 10 = 0

We need two numbers that multiply to 10 and add to -7.

Those numbers are -2 and -5.

(x−2)(x−5)=0(x - 2)(x - 5) = 0

Solutions: x=2x = 2 and x=5x = 5


We set the base equal to -1:

x2−7x+11=−1x^2 - 7x + 11 = -1

x2−7x+12=0x^2 - 7x + 12 = 0

We need two numbers that multiply to 12 and add to -7.

Those numbers are -3 and -4.

(x−3)(x−4)=0(x - 3)(x - 4) = 0

Potential solutions: x=3x = 3 and x=4x = 4

For (−1)exponent=1(-1)^{\text{exponent}} = 1, the exponent must be even.

When x=3x = 3: Exponent = 32−13(3)+42=9−39+42=123^2 - 13(3) + 42 = 9 - 39 + 42 = 12 (even)

When x=4x = 4: Exponent = 42−13(4)+42=16−52+42=64^2 - 13(4) + 42 = 16 - 52 + 42 = 6 (even)

Valid solutions: x=3x = 3 and x=4x = 4


We set the exponent equal to 0:

x2−13x+42=0x^2 - 13x + 42 = 0

We need two numbers that multiply to 42 and add to -13.

Those numbers are -6 and -7.

(x−6)(x−7)=0(x - 6)(x - 7) = 0

Potential solutions: x=6x = 6 and x=7x = 7

We need to ensure the base isn't 0 (since 000^0 is undefined).

When x=6x = 6: Base = $6^2 - 7(6) + 11 = 36 - 42 + 11 = 5

eq 0$

When x=7x = 7: Base = $7^2 - 7(7) + 11 = 49 - 49 + 11 = 11

eq 0$

Valid solutions: x=6x = 6 and x=7x = 7


All distinct positive integer solutions:

From Case 1: x=2,5x = 2, 5

From Case 2: x=3,4x = 3, 4

From Case 3: x=6,7x = 6, 7

Total count: 6 distinct solutions

When solving exponential equations equal to 1, we always check all three cases systematically. This approach ensures we don't miss any solutions.

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