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evey
Lv 4
evey asked in Science & MathematicsMathematics · 1 decade ago

another math question.... i've attempted it but im horrible.?

the product of two consecutive positive intergers is 11 more than their sum. Find the intergers.

Thanks guys-

Evey

21 Answers

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  • 1 decade ago
    Favorite Answer

    1st integer—x:

    x(x + 1) = x + x + 1 + 11

    x² + x = 2x + 12

    x² - 1/2x = 12 + (- 1/2)²

    x² - 1/2x = 48/4 + 1/4

    (x - 1/2)² = 49/4

    x - 1/2 = 7/2

    x = 8/2 or 4

    2nd integer:

    = 4 + 1

    = 5

    Answer: 4 and 5 are the integers.

  • ?
    Lv 7
    1 decade ago

    Let x be the first positive integer

    then x+1 is the second

    x(x+1)= x +(x+1) + 11, the right side is the product of consecutive positive integers, the left side is the sum of the positive integers plus 11

    x^2 + x = 2x + 12

    x^2 -x - 12 = 0

    factor

    (x-4)(x+3) = 0

    x - 4 = 0 so x = 4

    x + 3 = 0 so x would be -3 but you are dealing with positive integers so -3 is not an answer

    the integers are 4, and 5 the product is 20 and the sum is 9 and the product is indeed 11 more than the sum

  • Anonymous
    1 decade ago

    let me break it down for you

    the product -- this means we're talking about multiplying numbers together

    of two -- well that makes it easy, there's only two numbers to multiply

    consecutive -- the numbers are in order as according to...

    positive integers -- yes, it's spelled i-n-t-e-g-e-r-s, no R in the middle. positive means the numbers are greater than zero, integers are whole numbers. so "two consecutive positive integers" means a positive integer and the very next one in counting order. for example, 1 and 2, or maybe 2 and 3, or perhaps 3 and 4. well, we shall find out. note that if we subtract the first number from the second number we always get 1. so if we let x represent the smaller number, then we can represent the next consecutive integer after x as x+1.

    alright, I think we can start taking bigger steps

    the product...is 11 more than their sum

    well the product of x and x+1 is simply x(x+1)

    their sum means we add them together: x + x+1, which simplifies to 2x+1

    if the product is more (11 more in fact) than the sum, that means it is a bigger number. so if we start with their sum, how do we make that a bigger number, specifically a bigger number that is 11 more? seems painfully obvious, doesn't it? we just add 11 to that sum. so now we have an equation.

    product = sum + 11, which is

    x(x+1) = 2x + 1 + 11

    let's perform the multiplication indicated on the left, and simplify the right

    x^2 + x = 2x + 12

    now subtract what's on the right from both sides

    x^2 - x -12 = 0

    I think we can factor

    (x - 4)(x + 3) = 0

    if two numbers multiplied together equal zero, then one of them must be zero

    so if x-4=0, then x=4

    and if x+3=0, then x=-3

    hence we have two possible solutions: x=4, x=-3

    but the problem said we were looking for positive integers.

    therefore x=4 is what we want. now remember x was the first integer. what was the second one? none other than x+1, which in this case is 4+1=5.

    now we are finally done. 4 and 5 are the numbers we sought.

  • 1 decade ago

    Let x be the first integer

    x + 1 will be the second integer

    (x)(x+1) = x+x+1+11 (add 11 to this side because the product is 11 more, so to make this an equation we must make both sides equal)

    x^2+x = 2x+12

    x^2-x-12 = 0 (now we must factor)

    (x-4)(x+3) = 0

    x = -3, 4

    Now we go back to our original equation x values and plug -3 and 4 in for them.

    For x = -3

    First Integer = -3

    Second Integer = (-3) + 1 = -2

    We know -3 and -2 work because there product (6) is 11 more than their sum (-5).

    For x = 4

    First Integer = 4

    Second Integer = (4) + 1 = 5

    We know 4 and 5 work because there product (20) is 11 more than their sum (9).

    So you have two sets of integers (-3 and -2) and (4 and 5).

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  • Oliver
    Lv 4
    1 decade ago

    Let the first integer = x. Then the other integer is x + 1...

    (x)(x + 1) = x + (x + 1) + 11

    x^2 + x = 2x + 12

    x^2 - x - 12 = 0

    (x - 4)(x + 3) = 0

    Therefore, x = 4 or -3. As we are told the integers are positive, just take x = 4. Therefore, x + 1 = 4 + 1 = 5.

    The two consecutive integers are 4 and 5.

  • Anonymous
    1 decade ago

    4 and 5

  • Anonymous
    1 decade ago

    4 and 5

  • 1 decade ago

    4 and 5

  • 1 decade ago

    Let the 2 consecutive positive integers be n , n+1:

    n(n+1) = 11 + n + (n+1) = 12 + 2n

    n^2 -n -12 = 0

    (n-4)(n+3) = 0

    n = 4, n = -3 .

    n = -3 is dropped since we require positive integers.

    So, the answer is 4 and 5

  • Anonymous
    1 decade ago

    Product- The answer to a multiplication problem.

    Consecutive - In a row.

    Positive - 1,2,3,4,5......

    Integers- a set of whole numbers and there opposites. -3,-2,-1,0,1,2,3.

    Sum- Answer ot an addition problem

    lets start at the beginning

    1 x 2 = 3

    1 + 2= 3...

    So its not 1 & 2.

    2&3.

    2 x 3 = 6

    2 +3 = 5

    nope.

    3 & 4.

    3 x 4 = 12

    3 + 4 = 7

    nope.

    4 & 5.

    4 x 5 = 20

    4 + 5 = 9

    20 -9 = 11

    Yes!

    So ur answer is 4 & 5

    4 x 5 = 20

    then 5 + 4 = 9

    20 - 9 = 11

    :D

    -xoxo

  • ?
    Lv 4
    1 decade ago

    Let x be the first number so x +1 is the number after it

    x(x + 1) = x + (x + 1) + 11

    x^2 + x = 2x +12

    x^2 + x - 2x - 12 = 0

    x^2 - x - 12 = 0

    (x - 4)(x + 3) = 0

    x = 4, -3

    Since it can only be a positive number it is 4 and 5

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