Question

I need to know how to do this number 13 and the question

Answer 1

By 4

`-8x-20y=-4`

Explanation:

We have the following system of equations:

`\begin{gathered} -2x-5y=-1 \\ 8x+4y=16 \end{gathered}`

If we want to solve the system by means of the elimination method, the coefficients of one of the unknowns must be the same with the opposite sign, in such a way that when added, they are eliminated.

Since we must multiply is the first equation, we look at the unknown x, they already have an opposite sign, therefore we must multiply by a number that multiplied by 2, is equal to 8.

This number is 4, since 2 multiplied by 4 equals 8.

After multiplying by 4, the equation would look like this:

`\begin{gathered} 4\cdot(-2x-5y=-1) \\ -8x-20y=-4 \end{gathered}`