Answer:
[tex]P+Q-R=11x^2-4xy+10y^2[/tex]
Step-by-step explanation:
I'm assuming the 2's at the end of some of the terms are meant to be exponents. So here we have
[tex]P=3x^2+xy-5y\\Q=2x^2-xy+3y^2\\R=-6x^2+4xy-7y^2[/tex]
and we're asked to find P + Q - R. Let's handle these operations left to right to cut down on clutter. Starting with P + Q, our first job should be to combine all the like terms we can. 3x² + 2x² = 5x², and xy - xy = 0, but we still can't do anything with the terms -5y and 3y². So far, this gives us
[tex]P+Q=5x^2-5y+3y^2[/tex]
Now let's handle subtracting R from this sum. The pairs of like terms here are 5x² and -6x², and 3y² and -7y². Subtracting these parts gives us 5x² - (-6x²) = 11x² and 3y² - (-7y²) = 10y², and we can subtract off the remaing 4xy in R to give us
[tex]P+Q-R=11x^2-4xy+10y^2[/tex]
