Question

12. Find the solution to the system of equations by

using
substitution.
y = -2x + 13
4x + 8y = 20
A)(-7,-1)
B)(4,5
C)(7,-1)
D)(-3,7)

Answer 1

Answer: C) x = 7, y = -1

Explanation:

=> y = -2x + 13 (Eq. 1)
=> 4x + 8y = 20 (Eq. 2)

Substitute value of ‘y’ from Eq. 1 in 2 :-

4x + 8y = 20
4x + 8(-2x + 13) = 20
4x + -16x + 104 = 20
-12x + 104 = 20
-12x = 20 - 104
-12x = -84
12x = 84
x = 84/12
=> x = 7

Substitute value of ‘x’ in Eq. 1 :-

y = -2x + 13
y = -2(7) + 13
y = -14 + 13
=> y = -1

Therefore, x = 7, y = -1 which can be written in an ordered pair as (7,-1).