SOLUTION: The difference between two integers is 5. If the reciprocal of the smaller is added to twice the reciprocal of the larger the result is 23/66. Find the two integers.

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Question 1043768: The difference between two integers is 5. If the reciprocal of the smaller is added to twice the reciprocal of the larger the result is 23/66. Find the two integers.
Found 3 solutions by josgarithmetic, Edwin McCravy, MathTherapy:
Answer by josgarithmetic(39631) About Me  (Show Source):
Answer by Edwin McCravy(20066) About Me  (Show Source):
You can put this solution on YOUR website!


Let y = the larger integer
Let x = the smaller integer

system%28y-x=5%2C%281%2Fx%29%2B2%281%2Fy%29=23%2F66%29

y%22%22=%22%225%2Bx

Substitute (5+x) for y in

%281%2Fx%29%2B2%281%2Fy%29%22%22=%22%2223%2F66%29

%281%2Fx%29%2B2%281%2F%285%2Bx%29%29%22%22=%22%2223%2F66%29

%281%2Fx%29%2B2%2F%285%2Bx%29%22%22=%22%2223%2F66%29

LCD = 66x(5+x)

Multiply each numerator by every factor of
the denominator which is not under it:

1%2866%285%2Bx%29%29%2B2%2866x%29%22%22=%22%2223%28x%285%2Bx%29%29%29

66%285%2Bx%29%2B132x%22%22=%22%2223x%285%2Bx%29

330%2B66x%2B132x%22%22=%22%22115x%2B23x%5E2

330%2B198x%22%22=%22%22115x%2B23x%5E2

Subtract 115x from both sides

330%2B83x%22%22=%22%2223x%5E2

Subtract 23x2 from both sides

to get 0 on the right side

-23x%5E2%2B330%2B83x%22%22=%22%220

Arrange left side in descending order:

-23x%5E2%2B83x%2B330%22%22=%22%220

Multiply through by -1:

23x%5E2-83x-330%22%22=%22%220

There may be a way to factor that but
when the numbers are that big, it's
easier to use the quadratic formula,
especially if you have a calculator:

x+%22%22=%22%22+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29+

x+%22%22=%22%22+%28-%28-83%29+%2B-+sqrt%28+%28-83%29%5E2-4%2823%29%28-330%29+%29%29%2F%282%2A%2823%29%29+

x+%22%22=%22%22+%2883+%2B-+sqrt%286889%2B30360%29%29%2F46+

x+%22%22=%22%22+%2883+%2B-+sqrt%2837249%29%29%2F46+

x+%22%22=%22%22+%2883+%2B-+193%29%2F46+

Using the +

x+%22%22=%22%22+%2883+%2B+193%29%2F46+

x=276%2F46

x%22%22=%22%226

Using the -

x+%22%22=%22%22+%2883+-+193%29%2F46+

x%22%22=%22%22-110%2F46

x%22%22=%22%22-55%2F23

The problem calls for an integer.  That's not
an integer, so we can discard that value of x.

So x = 6

Substitute into

y%22%22=%22%225%2Bx

y%22%22=%22%225%2B6

y%22%22=%22%2211

Answers: Larger integer = 11, Smaller integer = 6

Edwin

Answer by MathTherapy(10559) About Me  (Show Source):
You can put this solution on YOUR website!




The difference between two integers is 5. If the reciprocal of the smaller is added to twice the reciprocal of the larger the result is 23/66. Find the two integers.
Let the larger be L
Then smaller = L – 5
We then get: 1%2F%28L+-+5%29+%2B+2%281%2FL%29+=+23%2F66_______1%2F%28L+-+5%29+%2B+2%2FL+=+23%2F66
66L + 2(66)(L – 5) = 23L(L – 5) -------- Multiplying by LCD, 66L(L – 5)
66L+%2B+132L+-+660+=+23L%5E2+-+115L
198L+-+660+=+23L%5E2+-+115L
23L%5E2+-+115L+-+198L+%2B+660+=+0
23L%5E2+-+313L+%2B+660+=+0
23L%5E2+-+253L+-+60L+%2B+660+=+0
23L(L – 11) – 60(L – 11) = 0
(L – 11)(23L – 60) = 0
L, or highlight_green%28matrix%281%2C2%2C+Larger%2C+integer+=+11%29%29 OR L = 60%2F23 (ignore)