Questions:

(a) What is a simplified expression for (x + y) – (x – y)?

(b) Carlotta thinks that [tex]3y + 5y^3[/tex] is the same as [tex]8y^4[/tex]. Which statement shows that it is NOT the same?

Answer:

[tex](x + y) – (x – y) =2y[/tex]

[tex]3y + 5y^3 \ne 8y^4[/tex]

Step-by-step explanation:

Solving (a):

Given

[tex](x + y) – (x – y)[/tex]

Required

Simplify

[tex](x + y) – (x – y)[/tex]

Open brackets

[tex](x + y) – (x – y) = x + y – x + y[/tex]

Collect Like Terms

[tex](x + y) – (x – y) = x – x+ y + y[/tex]

[tex](x + y) – (x – y) = y + y[/tex]

[tex](x + y) – (x – y) =2y[/tex]

Solving (b):

Given

[tex]3y + 5y^3[/tex] and [tex]8y^4[/tex]

Required

Which expression shows they are not the same

The expression that shows this is:

[tex]3y + 5y^3 \ne 8y^4[/tex]

Take for instance; y=2

Substitute 2 for y in [tex]3y + 5y^3 \ne 8y^4[/tex]

[tex]3*2 + 5*2^3 \ne 8*2^4[/tex]

Evaluate all exponents

[tex]9 + 5*8 \ne 8*16[/tex]

[tex]9 + 40 \ne 128[/tex]

[tex]49 \ne 128[/tex]

The above expression supports [tex]3y + 5y^3 \ne 8y^4[/tex]

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