Question

Solve using the substitution method.

2x – y = –20
y = –2x

A. (–5, 10)
B. (–3, 6)
C. No solution
D. (–8, 16)

Answer 1

A. (-5, 10)

Explanation:

`\left\{\begin{array}{ccc}2x-y=-20&(1)\\y=-2x&(2)\end{array}\right\\\\\text{Substitute (2) to (1):}\\\\2x-(-2x)=-20\\2x+2x=-20\\4x=-20\qquad\text{divide both sides by 4}\\x=-5\\\\\text{Put the value of }\ x\ \text{to (2):}\\\\y=-2(-5)\\y=10`

Answer 2

Answer:option A

Explanation:

2X-Y=20

2X-(-2X)=-20

2X+2X=-20

4X=-20

X=-20/4=-5

So we have: Y= -2(-5)=10