multiply 1st eqn by 7
add to 2nd eqn to eliminate x
solve for y , then substitute back to find x
y =1/4x - 4 : y = -7/4x + 4
I need help with this one...has to be solved by elimination. Thanks
3 answers
y = y
1 / 4 x - 4 = - 7 / 4 x + 4
Add 7 / 4 x to both sides
1 / 4 x - 4 + 7 / 4 x = - 7 / 4 x + 4 + 7 / 4 x
8 / 4 x - 4 = 4
2 x - 4 = 4
Add 4 to both sides
2 x - 4 + 4 = 4 + 4
2 x = 8
Divide both sides by 2
x = 8 / 2
x = 4
Replace this value in equation for y.
y = 1 / 4 x - 4 = x / 4 - 4 = 4 / 4 - 4 = 1 - 4 = - 3
OR
y = - 7 / 4 x + 4 = - 7 ∙ x / 4 + 4 = - 7 ∙ 4 / 4 + 4 = - 7 + 4 = - 3
Solution:
x = 4 , y = - 3
You can write this as:
( 4 , - 3 )
1 / 4 x - 4 = - 7 / 4 x + 4
Add 7 / 4 x to both sides
1 / 4 x - 4 + 7 / 4 x = - 7 / 4 x + 4 + 7 / 4 x
8 / 4 x - 4 = 4
2 x - 4 = 4
Add 4 to both sides
2 x - 4 + 4 = 4 + 4
2 x = 8
Divide both sides by 2
x = 8 / 2
x = 4
Replace this value in equation for y.
y = 1 / 4 x - 4 = x / 4 - 4 = 4 / 4 - 4 = 1 - 4 = - 3
OR
y = - 7 / 4 x + 4 = - 7 ∙ x / 4 + 4 = - 7 ∙ 4 / 4 + 4 = - 7 + 4 = - 3
Solution:
x = 4 , y = - 3
You can write this as:
( 4 , - 3 )
-x/4 + y = -4. Standard form.
Multiply both sides by 4:
Eq1: -x + 4y = -16.
7x/4 + y = 4.
Multiply both sides by 4:
Eq2: 7x + 4y = 16.
Multiply Eq1 by -1 and add Eq1 and Eq2:
x - 4y = 16
7x + 4y = 16
Sum: 8x = 32
X = 4.
In Eq1, replace X with 4 and solve for Y:
-4 + 4y = -16.
Y = -3.
Multiply both sides by 4:
Eq1: -x + 4y = -16.
7x/4 + y = 4.
Multiply both sides by 4:
Eq2: 7x + 4y = 16.
Multiply Eq1 by -1 and add Eq1 and Eq2:
x - 4y = 16
7x + 4y = 16
Sum: 8x = 32
X = 4.
In Eq1, replace X with 4 and solve for Y:
-4 + 4y = -16.
Y = -3.