SOLUTION: On the word problems using multiplication is throwing me off, such as this problem "Find two numbers whose sum os 24 and whose product is 143"

Algebra ->  Problems-with-consecutive-odd-even-integers -> SOLUTION: On the word problems using multiplication is throwing me off, such as this problem "Find two numbers whose sum os 24 and whose product is 143"      Log On


   



Question 170611: On the word problems using multiplication is throwing me off, such as this problem "Find two numbers whose sum os 24 and whose product is 143"
Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
lets call the 2 numbers a and b
:
sum of the numbers is a+b which equals 24----------------->a+b=24...eq 1
:
the product of the numbers is ab which equals 143.-------->ab=143...eq 2
:
lets take eq 1 and write it in terms of a--->a=24-b
:
take a's value from eq 1 and plug it into eq 2
:
(24-b)b=143---distribute--->24b-b%5E2=143
:
b%5E2-24b%2B143=0
so b can be 11 or 13 if b is 11 then a is 13 if b is 13 the a is 11
:our two numbers aresystem%2811%2C13%29
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ab%5E2%2Bbb%2Bc=0 (in our case 1b%5E2%2B-24b%2B143+=+0) has the following solutons:

b%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-24%29%5E2-4%2A1%2A143=4.

Discriminant d=4 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--24%2B-sqrt%28+4+%29%29%2F2%5Ca.

b%5B1%5D+=+%28-%28-24%29%2Bsqrt%28+4+%29%29%2F2%5C1+=+13
b%5B2%5D+=+%28-%28-24%29-sqrt%28+4+%29%29%2F2%5C1+=+11

Quadratic expression 1b%5E2%2B-24b%2B143 can be factored:
1b%5E2%2B-24b%2B143+=+1%28b-13%29%2A%28b-11%29
Again, the answer is: 13, 11. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-24%2Ax%2B143+%29


: