Question

What is the value of k, if the value of Dy, for the equations 3x+y=1 and 2x-ky-3 is 7? (A) 22 (B) - 22 (C) 11 (D) - 11​

Answer 1

Answer:

$solve\:for\:x,\:3x+y=1\quad :\quad x=\frac{1-y}{3}$

Step-by-step explanation:

$\mathrm{Subtract\:}y\mathrm{\:from\:both\:sides}$

$3x+y-y=1-y$

$3x=1-y$

$\mathrm{Divide\:both\:sides\:by\:}3$

$\frac{3x}{3}=\frac{1}{3}-\frac{y}{3}$

$x=\frac{1-y}{3}$

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since,x=2

y=-3

2×2-k(-3)=3

4+k=3

k=-1