Question

A student is trying to solve the system of two equations given below: Equation P: a + b = 6 Equation Q: 4a + 2b = 19 Which of the following steps can be used to eliminate the a term? −1(4a + 2b = 19) −4(4a + 2b = 19) −4(a + b = 6) 4(a + b = 6)

Answer 1

`-4(a + b = 6)`

Explanation:

Given

`a + b = 6`

`4a + 2b = 19`

Required

Eliminate a

Multiply the first equation by -4

`-4(a + b = 6)`

Add to the second equation

`-4(a + b = 6) + (4a + 2b = 19)`

Solve brackets

`(-4a -4b = -24) + (4a + 2b = 19)`

Open bracket

`-4a + 4a -4b + 2b = -24 + 19`

`-4b + 2b = -24 + 19`

At this point, a has been eliminated;

From the list of given options, the option that answers the question is
`-4(a + b = 6)`