A local high school held a two-day fundraiser selling lunches. The equations shown represent the amount of money the school coll
ected during the two days. {12x + 4y = 15232x + 12y = 420 In the equations, x represents the cost of a chicken lunch and y represents the cost of a vegetarian lunch. Which is the cost of the vegetarian lunch?
y = (152(32) -420(12))/(4(32) -12(12)) = -176/-16 = 11
The cost of the vegetarian lunch is 11.
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<em>Comment on Cramer's Rule</em>
For equations ...
ax +by =c
dx +ey = f
The solutions are ...
x = (bf -ey)/(bd -ea)
y = (cd -fa)/(bd -ea) . . . . note the denominators are the same expression
Once you memorize the pattern of products, this can be the simplest way to solve a pair of equations--especially if you only need one of the variable values.
