Question

When x-y=3 work out the value of y-x

Answer 1

The value of y-x is (-3)

Solution:

Given: The value of x-y=3

To find: The value of y-x

`\bold{x-y=3\rightarrow (1)}`

Let's multiply the equation (1) by (- 1) on both sides,

`\Rightarrow\bold{(x - y)*(- 1) = 3*(- 1)}`

`\Rightarrow\bold{-(x-y)=-3}`

On multiplying the sign,

`\Rightarrow\bold{(-x+y)=-3}`

The above equation can also be written as,

`\Rightarrow\bold{y-x=-3\rightarrow \text{(The required equation)}}`

Multiplication of signs:

`\Rightarrow( + )*( + ) = ( + )`

`\Rightarrow( + )*( - ) = ( - )`

`\Rightarrow( - )*( + ) = ( - )`

`\Rightarrow( - )*( - ) = ( + )`

In simpler terms, when we multiply two integers with the same signs, the result is always positive and when we multiply two integers with different signs, the result is always negative.