The product of the number that is 4 less than a number and the number that is 5 more than it is 360. What is the positive original number?
Answer and explanation
Correct answer: 19
Let the original number be \(x\). Then \((x-4)(x+5)=360\), which gives \(x^2+x-380=0\). Factoring, \((x-19)(x+20)=0\), so \(x=19\) or \(x=-20\). Since the question asks for the positive number, the answer is \(19\). In such problems, write “4 less” as \(x-4\) and “5 more” as \(x+5\).
Frequently asked questions
What is the correct answer to this question?
19
Why is this the correct answer?
Let the original number be \(x\). Then \((x-4)(x+5)=360\), which gives \(x^2+x-380=0\). Factoring, \((x-19)(x+20)=0\), so \(x=19\) or \(x=-20\). Since the question asks for the positive number, the answer is \(19\). In such problems, write “4 less” as \(x-4\) and “5 more” as \(x+5\).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Word Problems and Applications.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
