How do you evaluate #2x ^ { 2} y# if # x = 2\frac { 1} { 2} ,y = - 3\frac { 3} { 5}#?

2 Answers
Jacq
Oct 4, 2017

#2x^2y=-45#

Explanation:

You can evaluate #2x^2y# by subbing in the given points, #x=2 1/2# and #y=-3 3/5#.

First, it's best to turn these fractions into improper fractions:
#x=5/2#
#y=-18/5#

Subbing these into the expression we get:
#2x^2y#
#=2(5/2)^2(-18/5)#
#=2(25/4)(-18/5)#

These fractions can be further simplified before you multiply them together:

#=1(25/2)(-18/5)#
#=5/2(-18/1)#
#=5/1(-9)#
#=-45#

So in short, #2x^2y=-45#

Jim G.
Oct 4, 2017

#-45#

Explanation:

#"change the mixed numbers into "color(blue)"improper fractions"#

#rArr2 1/2=5/2" and "3 3/5=18/5#

#rArr2x^2y#

#=2xx(5/2)^2xx-18/5#

#=2xx25/4xx-18/5#

#color(blue)"cancel common factors "# on numerators/denominators.

#=cancel(2)^1xxcancel(25)^5/cancel(4)^2xx-18/cancel(5)^1#

#=1xx5/cancel(2)^1xx-cancel(18)^9/1#

#=1xx5xx-9=-45#

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