A student is trying to solve the system of two equations given below: Equation P: y + z = 6 Equation Q: 8y + 7z = 1 Which of these is a possible step used in eliminating the y-term? (y + z = 6) ⋅ −8 (y + z = 6) ⋅ 7 (8y + 7z = 1) ⋅ 7 (8y + 7z = 1) ⋅ 8
Mathematics · High School · Tue Nov 03 2020
Answered on
A student is trying to solve the system of two equations:
P: y + z = 6 ..eqn¹
Q: 8y + 7z = 1 ..eqn²
Which of these is a possible step used in eliminating the y-term?
a. (y + z = 6)
b. −8 (y + z = 6)
c. 7 (8y + 7z = 1)
d. 8
For eliminating one variable we have to make their constant common.
So for eliminating y we have to multiply eqn¹ with -8, so the option b is correct.
-8( y+ z) = -8(6)
-8y -8z = -48 ..eqn³
Now add (eqn² + eqn³):
8y +7z -8y -8z = 1 -48
-z = -47
z= 47
Put, z= 47 in eqn¹:
y + z =6
y + 47 = 6
y = 6-47
y= -41