# evaluate (2x/5+3y/4-4z/7)to the power of 2this is from chapter Expansions(including substitution)

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### 1 Answer

Evaluate is not the right word here, since that means to find the value. I believe you mean "expand" since the chapter is called expansions and I don't see anything else to do with this problem.

Remember, squaring means multiplying by itself. So you're interested in` `

` ``((2x)/5+(3y)/4-(4z)/7)``((2x)/5+(3y)/4-(4z)/7)`

Now you just use the distributive property 3 times to multiply these trinomials:

`(2x)/5*(2x)/5+(2x)/5*(3y)/4-(2x)/5*(4z)/7`

` ``+(3y)/4*(2x)/5+(3y)/4*(3y)/4-(3y)/4*(4z)/7`` `

` ``-(4z)/7*(2x)/5-(4z)/7*(3y)/4+(4z)/7*(4z)/7`` `

It's a bit tedious, but now you combine all the like terms. I'll start by multiplying each pair of fractions:

`4/25x^2+3/10xy-8/35xz`

`+3/10xy+9/16y^2-3/7yz`

`-8/35xz-3/7yz+16/49z^2`

Now combine the like terms

`4/25x^2+3/5xy-16/35xz+9/16y^2-6/7yz+16/49z^2`

And you're done!