Question

Becket needs to solve the system of equations using elimination.

-2x+4y=-2
(6x-y=28)
Which correctly describes the first step Becket should take?
A. Multiply each term in the 1st equation by -3
B. Multiply each term int he 1st equation by 3
C. Multiply each term in the 2nd equation by -4
D. Both B and C would work

Answer 1

Explanation:

step 1

Multiply each term in the second equation with 4

step 2

Add equation 1 to equation 2

step 3

make x subject of formula and obtain value of X

step 4

substitute value of X in equation 1 and find Y

Answer 2

B. Multiply each term in the 1st equation by 3

Explanation:

• A is incorrect because multiplying the entire 1st equation by -3 will give you 6x - 12y = 6. This does not cancel with either x or y term in the second equation.
• B is correct because by multiplying the entire 1st equation by 3 will give you -6x + 12y = -6. The -6x term will cancel (or eliminate) the 6x term in the second equation.
• C is incorrect because multiplying the entire 2nd equation by -4 will give you -24x + 4y = -112. This does not cancel with either x or y term in the 1st equation.
• D is incorrect because C was proven to be incorrect.