Question

Which one (a, b, c or d) is not true if x-5y=7

Answer 1

Answer:

Step-by-step explanation:

answer : B

y = (x-7)/-5

-5y = x -7

x +5y  = 7  no x-5y=7

Answer 2

Answer:

$\large\boxed{B.\ y=\dfrac{x-7}{-5}}$

Step-by-step explanation:

$x-5y=7\qquad\text{add 5y to both sides}\\\\x-5y+5y=5y+7\\\\x=5y+7\to\boxed{A}\\------------\\x-5y=7\qquad\text{subtract x from both sides}\\\\-5y=-x+7\qquad\text{divide bothg sides by (-5)}\\\\y=\dfrac{-x+7}{-5}\\\\y=\dfrac{x-7}{5}\to\boxed{\text{it's not equal to expression in B.}}\\------------$

$C.\ 4x+2y+7=5x-3y\qquad\text{subtract}\ 4x\ \text{and}\ 2y\ \text{from both sides}\\\\7=x-5y\to \boxed{OK}\\----------\\D.\ 3x+10y=4x+5y-7\qquad\text{subtract}\ 4x\ \text{and}\ 5y\ \text{from both sides}\\\\-x+5y=-7\qquad\text{change the signs}\\\\x-5y=7\to\boxed{OK}$