Question

Suppose that four times the square of a number equals 40 times that number. what is the number.

Answer 1

Given:

Let the number be x

According to the statement,

`4x^2=40\text{x}`

Simplifying for x,

`\begin{gathered} 4x^2=40x \\ 4x^2-40x=0 \\ 4x(x-10)=0 \\ 4x=0,x-10=0 \\ x=0,x=10 \end{gathered}`

Hence, the number can be 0 or 10.