Problem 1
x(x + 1) = x + (x + 1) + 55
x² + x = x + x + 1 + 55
x² - x - 56 = 0
(x - 8)(x + 7) = 0
x = 8 , x = - 7
Answer is 8 and 9
Problem 2
x ² + 6 = 22
x ² = 16
x = ± 4
Problem 3
x(x + 1) = 600
x² + x - 600 = 0
(x + 25)(x - 24) = 0
x = 24 is accepted
Pages are 24 and 25
2007-10-22 07:29:36
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answer #1
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answered by Como 7
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Hai David,
1. the product of two consecutive positive integers is 55 more than their sum. find the integers
Let the positive integers be n & n+1.
Then, n(n+1) = n + (n+1) + 55
=> n^2 + n = 2n + 1 + 55
=> n^2 - n - 56 = 0
=> n^2 - 8n + 7n - 56 = 0
=> n(n-8) + 7(n-8) =0
=> (n-8)(n+7)=0
=> n=8 or (-)7
Taking only the positive integer, we get n = 8.
The integers are 7 & 8.
2. if 6 is added to the square of a number, the result is 22. find all such numbers.
Let N be the number.
Then, N^2 + 6 = 22
=> N^2 = 22-6 = 16
=> N = sq. rt. 16 = +4 or (-)4
The numbers are (+)4 & (-)4
3. the product of the page numbers on two facing pages of a book is 600. find the page
Facing pages indicates that the page numbers are consecutive.
Let the numbers be m & m+1
Then, m(m+1) = 600
=> m^2 + m - 600 = 0
=> m^2 + 25m - 24m - 600 = 0
=> m(m+25) - 24(m+25) = 0
=> (m+25)(m-24) = 0
=> m = (+)24 or (-)25
Taking only the positive value, m = 24
=> m+1 = 25
So, the page numbers are 24 & 25.
2007-10-22 03:37:27
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answer #2
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answered by WishInvestor 3
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problem 1:
Suppose 1st integer =x
So x * (x+1) = x +(x+1) +55
x^2 + x = 2x + 56
x^2 - x - 56 = 0
Use factorisation.
x^2 -7x +8x - 56=0
x(x-7) +8(x-7)=0
(x+8)(x-7)=0
The possible values of x are 7, -8, but since it's given that x is a positive integer, it can only be 7.
So the two integers are 7 & 8.
problem 2
Suppose the number is x
So x^2 + 6 = 22
x^2 = 16
x = 4, -4
problem 3
Let the left page number = x
So the right page number = x+1
x(x+1) = 600
x^2 + x - 600 = 0
x^2 +25x-24x - 600 = 0
x(x+25) -24(x+25)=0
(x-24)(x+25)=0
The possible values of x are 24 and -25, but since a page number can't be negative, the answer is 24.
So the page numbers are 24 and 25.
2007-10-22 03:35:49
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answer #3
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answered by al 2
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problem 1
Let x = 1st integer, x + 1 = 2nd integer.
x(x + 1) = x + x + 1 + 55
x^2 + x = 2x + 56
x^2 - x - 56 = 0
(x - 8)(x + 7) = 0
x = 8, x = - 7
Answer: 1st set: 1st integer is 8, the 2nd is 9; or 2nd set: 1st integer is - 7, the second is - 6
Proof (1st set: 8 and 9):
8 * 9 = 8 + 9 + 55
72 = 72
Proof (2nd set: - 7 and - 6):
- 7 * - 6 = - 7 + (- 6) + 55
42 = - 7 - 6 + 55
42 = 42
problem 2
Let x = the number
x^2 + 6 = 22
x^2 = 16
x = 4
Answer: the number is 4
Proof:
= 4^2 + 6
= 16 + 6
= 22
problem 3
Let x = 1st page; x + 1 = opposite page
x(x + 1) = 600
x^2 + x - 600 = 0
(x - 24)(x + 25) = 0
Answer: 1st page is 24, opposite page is 25.
Proof:
= 24 * 25
= 600
2007-10-22 03:26:20
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answer #4
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answered by Jun Agruda 7
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1) set up an algebraic equation: x(x+1)=55+x+(x+1)
next simplify both sides: x^2+x=56+2x
subtract 56+2x from both sides: x^2-x-56=0
factor: (x-8)(x+7)=0
solve: x=8 or -7
since the problems says a positive integer, the answer must be 8 and 9
2)again set up an algebraic equation: 6+x^2=22
now subtract 6 from both sides: x^2=16
now take the square root of both sides:x=4 or -4
the answer is 4 or -4
3)Set up an equation: x(x+1)=600
multiply through: x^2+x=600
subtract 600 from both sides: x^2+x-600=0
factor: (x-24)(x+25)=0
solve: x=24 or -25
book pages can't be negative, so the page numbers must be 24 and 25.
2007-10-22 03:21:01
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answer #5
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answered by guamo17 1
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Problem-1
let the two consecutive positive integeres be n and n+1
n(n+1) = n+n+1+55
n^2+n = 2n + 56
n^2 - n - 56 = 0
n^2 - 8n + 7n - 56 = 0
n(n-8)+7(n-8) = 0
n=8 or -7 (cancelled as it can't be -ve)
hence the numbers are 8 & 9
Problem-2
let the number be n
n^2 + 6 = 22
n^ = 16
n = 4 or -4
problem-3
let the number of first of the two pages be n and then the next would be n+1
n(n+1) = 600
n^2+n-600 = 0
n^2+25n-24n-600 = 0
n(n+25)-24(n+25) = 0
n = 25 & -25 (cancelled as page number can't be negative)
hence the numbers are 24 & 25
2007-10-22 06:17:11
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answer #6
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answered by Shreya S 3
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ans1 is 8 & 9
ans2 is +4 & -4
&
ans3 is 24 & 25
i m correct na?
2007-10-22 03:14:23
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answer #7
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answered by Varun G 2
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ans1 is 8& 9.
ans2 is +4and -4
ans3 is 24and 25.
2007-10-22 03:33:33
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answer #8
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answered by check this out 2
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