Date: Wed, 24 Mar 1999 13:20:23 0800
A second number is 4 less than a first number. The product of the second number and 3 more than the first number is 18. Find the pair of numbers.
That is my question
My name is Anna and it is 11th grade math and I am a student
Hi Anna, There are 3 phases in solving the problem.
Phase 1: Translate from English to mathematics.
Phase 2: Do the mathematics.
Phase 3: Translate back into English.
Here is an approach the first translation.
Phase 1: First try to change the words into symbols.
The first sentence tells us that
the second number is 4 less than the first number.
Let f be the first number and s the second number then this sentence says
s is 4 less than f
translate this as
s = f  4
The second sentence tells us that
the product of the second number and 3 more than the first number is 18
That is
the product of s and 3 more than f is 18
or translated
s(f + 3) = 18
Phase 2:
Since s = f  4 and s(f + 3) = 18, we get (f  4)(f + 3) = 18. Moving the 18 to the left side of the equation, expanding and collecting like terms gives a quadratic that you can solve either by factoring or using the general quadratic formula. You will get 2 values for f and each one will give you a value for s since s = f  4 and so you will have 2 sets of answers.
Phase 3:
Write and English sentence that answers tha question.
I hope that this helps.
Jack and Penny
Go to Math Central
To return to the previous page use your browser's back button.
