Question

Solve the following simultaneous equations 5x+7y = 17 ; 7x+5y = 19​

Answer 1

Answer:

$x=2.\ y=1$

Step-by-step explanation:

$We\ are\ given\ the\ following\ pair\ of\ equations:\\5x+7y=17\\7x+5y=19\\Now,\\As\ the\ co-efficients\ of\ none\ of\ the\ algebraic\ terms\ match,\\We\ can\ take\ the\ LCM\ of\ their\ co-efficients;\\As\ the\ co-efficients\ of\ the\ x-terms\ are\ 5,7\ respectively;\\Their\ LCM\ is\ 35.$

$Hence,\\7(5x+7y)=7(17)\\-5(7x+5y)=-5(19)\\Hence,\\35x+49y=119\\-35x-25y=-95\\Hence,\\Adding\ the\ two\ equations\ we\ have:\\(35x+49y)+(-35x-25y)=(119)+(-95)\\(35x-35x)+(49y-25y)=119-95\\24y=24\\y=\frac{24}{24}=1$

$Now,\\Lets\ consider\ the\ First\ Equation:\\5x+7y=17\\Substituting\ y=1,\\5x+7*1=17\\5x+7=17\\5x=17-7\\5x=10\\x=\frac{10}{5}=2\\\\Together,\\x=2.\ y=1$