Solve the simultaneous equations 4x + 2y =20 and 8x + 6y =45
Let (1) be 4x + 2y =20 and (2) be 8x + 6y =45.First we want to eliminate either x or y so that we have an equation in terms of only one unknown. Lets eliminate x. If we multiply (1) by 2 we have2(4x + 2y) = 2(20) giving 8x + 4y =40. Now the x terms in both equations are the same. Next we subtract 2*(1) from (2) to give:(2) - 2*(1) : (8x + 6y) - (8x + 4y) = 45 - 40 giving 2y = 5. this can be rearranged to find y = 2.5.Finally, the the value for y can be substituted into either (1) or (2) to give the value of x: 4x + 2(2.5) =204x = 15x = 15/4 = 3.75
JR
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