Question 119176
a)

Anything with an equal sign is an <b>equation</b> which is not an expression. So {{{4r=5}}} is not an expression




b)


{{{6x^2+ 22xy + 20y^2}}} Start with the given expression



{{{6(3)^2+ 22(3)(-1) + 20(-1)^2}}} Plug in {{{x=3}}} and {{{y=-1}}}



{{{6(9)+ 22(3)(-1) + 20(-1)^2}}} Square 3 to get 9



{{{6(9)+ 22(3)(-1) + 20(1)}}} Square -1 to get 1



{{{54-66 + 20}}} Multiply



{{{8}}} Combine like terms



So {{{6x^2+ 22xy + 20y^2=8}}} when {{{x=3}}} and {{{y=-1}}}