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# Evaluation of Expressions

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I cannot find my error. Evaluate the expression if w=3/4, x=8, y=-2, and z=0.4

(wx+yz)/(wx-yz)

Dec 19, 2017

#1
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We already know the values of the given variables, so simply substitute the known value for the given value into the expression and evaluate carefully.

 $$\frac{wx+yz}{wx-yz}$$ Visually, a fraction is probably more attractive. Now, as aforementioned, plug in the values provided. $$\frac{\frac{3}{4}*8+(-2)(0.4)}{\frac{3}{4}*8-(-2)(0.4)}$$ Let's do the multiplication in the numerator and denominator first. $$\frac{\frac{24}{4}-0.8}{\frac{24}{4}+0.8}$$ Of course, 24/4=6, so we can simplift further. $$\frac{6-0.8}{6+0.8}$$ $$\frac{5.2}{6.8}$$ Leaving decimals in fraction is not desired, so let's eliminate those by multiplying the numerator and denominator by 10. $$\frac{52}{68}$$ The GCF of the numerator and denominator happen to be 4, so factor that out. $$\frac{13}{17}$$ There are no common factors, other than 1, that we can factor out. This fraction has an ugly corresponding decimal expansion, so I will not bother to leave that.
Dec 19, 2017
#2
+1

I found my error. It was a dumb one, as always.

Thanks!

TheXSquaredFactor  Dec 19, 2017