How many ordered pairs of integers ( x , y ) are there such that
( x − 1 0 ) ( x − 1 2 ) = 2 y ?
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what is that theorem?
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If 2 integers multiplied is a power of A then the integers must also be a power of A
draw the graph of 2^y and x^2-22x+120 they for sure intersect only at two points therefore ordered pair of (x,y) are 2.
i donot understand
But not necessarily they'll be lattice points.
A quadratic function intersects 2^y at 2 points knowing that the intersections stay in both the positive x and y directions
This is just like a product of two consecutive even numbers that are both powers of two or the product of their negatives. So we have two sets, the positives and negatives of 2 and 4.
With both 2 and 4 positive, x = 1 4 , y = 3 and with both negative, x = 8 , y = 3 .
assume x-10=a and x-12=b when b = a+2 >>>1 a,b should be on the fourmela 2^n >>>>2 from 1 & 2 >>>>> (a,b) = (2,4) , ( -2,-4 ) let x-10 = 4 >>> x=14 >>> y+3 comp >>>
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By the Fundamental Theorem of Arithmetic we must have both ∣ x − 1 0 ∣ and ∣ x − 1 2 ∣ as powers of 2 . Now the only two powers of 2 that differ by 2 are 2 and 4 . So since we always have that x − 1 0 > x − 1 2 , we can have either
x − 1 0 = 4 , x − 1 2 = 2 ⟹ x = 1 4 or
x − 1 0 = − 2 , x − 1 2 = − 4 ⟹ x = 8 .
In both cases y = 3 , so there are 2 ordered pairs, namely ( 1 4 , 3 ) and ( 8 , 3 ) .