Which of the following equations would not be consistent with 3y - 4x = 7?
Find two points on the line which has that equation:
Let y=1, then
3y - 4x = 7
3(1) - 4x = 7
3 - 4x = 7
-4x = 4
x = -1, so (1,-1) is one point on the line whose equation is 3y - 4x = 7
Let x=2, then
3y - 4x = 7
3y - 4(2) = 7
3y - 8 = 7
3y = 15
y = 5, so (2,5) is another point on the line whose equation is 3y - 4x = 7
Let's substitute (1,-1) and (2,5) in each of those. If they both satisfy the
equation, the equation is compatible with 3y - 4x = 7. But if either one of
the two points does not, then the equation is not compatible with 3y - 4x = 7.
A. - 8x = 6y - 14
Substituting (1,-1)
-8x = 6y - 14
-8(1) = 6(-1) - 14
-8 = -6 - 14
-8 = -20 [So (1,-1) DOES NOT satisfy it.]
So A. is NOT compatible with 3y - 4x = 7
-------------------------------------------------
B. 12y = - 9x + 28
Substituting (1,-1)
12y = -9x + 28
12(-1) = -9(1) + 28
-12 = -9 + 28
-12 = 19 [So (1,-1) DOES NOT satisfy it.]
So B. is NOT compatible with 3y - 4x = 7
-------------------------------------------------
C. - 16x + 28 = 12y
Substituting (1,-1)
-16x + 28 = 12y
-16(1) + 28 = 12(-1)
-16 + 28 = -12
12 = -12 [So (1,-1) DOES NOT satisfy it.]
So C. is NOT compatible with 3y - 4x = 7
-------------------------------------------------------
D. - 4x - 3y - 7 = 0
Substituting (1,-1)
-4x - 3y - 7 = 0
-4(1) - 3(-1) - 7 = 0
-4 + 3 - 7 = 0
-8 = 0 [So (1,-1) DOES NOT satisfy it.]
So D. is NOT compatible with 3y - 4x = 7
---------------------------------------------------------
E. - 56 - 24y = - 32x
Substituting (1,-1)
-56 - 24y = -32x
-56 - 24(-1) = -32(1)
-56 + 24 = -32
-32 = -32 [So (1,-1) satisfies it. So we substitute the other point.]
Substituting (2,5)
-56 - 24y = -32x
-56 - 24(5) = -32(2)
-56 -120 = -64
-176 = -32 [So (2,5) DOES NOT satisfies it.]
So E. is NOT compatible with 3y - 4x = 7
So NONE of them are compatible with 3y - 4x = 7
Edwin