Answer
a. 2x
b. x²
c. -2x
d. x²
Work Step by Step
a. When adding like terms you add the coefficients $1+1=2$.
b. When multiplying monomials you multiply the coefficients and the variables, then you multiply those two products $1\times1=1$ &
$(x)\times(x)=x²$.
c. Same as a. $-1+-1=-2$
d. Same as b. $-1\times-1=1$ & $(x)\times(x)=x²$