Question

3a. by what number should the top equation by multiplied by so that when the equations are combined, the xs are eliminated?\

$$\begin{cases}-x - 3y = 10\\\\8x + 5y = -4\\end{cases}$$

\bigcirc -3\bigcirc -5\bigcirc 3\bigcirc -8\bigcirc 5\bigcirc 8

Explanation:

Step1: Identify x coefficients

Top eq x-coeff: $-1$; Bottom eq x-coeff: $8$

Step2: Find multiplier for top eq

We need $(-1) \times k + 8 = 0$, solve for $k$.
$k = 8$
Verify: $(-1 \times 8) + 8 = -8 + 8 = 0$

Answer:

8