lhs(expr) returns the left-hand side of expr, which is equivalent to  $\mathrm{op}\left(1\,\mathrm{expr}\right)$.

rhs(expr) returns the right-hand side of expr, which is equivalent to $\mathrm{op}\left(2\,\mathrm{expr}\right)$.

The lhs and rhs commands are thread-safe as of Maple 15.

For more information on thread safety, see index/threadsafe.

$e≔y=a{x}^2+b$

$e≔y=a{x}^2+b$

$\mathrm{lhs}\left(e\right)$

$y$

$\mathrm{rhs}\left(e\right)$

$a{x}^2+b$

$r≔2..5$

$r≔2..5$

$\mathrm{lhs}\left(r\right)$

$2$

$\mathrm{rhs}\left(r\right)$

$5$

$t≔a::\mathrm{integer}$

$t≔a::\mathbb{Z}$

$\mathrm{lhs}\left(t\right)$

$a$

$\mathrm{rhs}\left(t\right)$

$\mathrm{integer}$

$h≔w+z<6$

$h≔w+z<6$

$\mathrm{lhs}\left(h\right)$

$w+z$

$\mathrm{rhs}\left(h\right)$

$6$

$f≔y=x^2+2x+1$

$f≔y=x^2+2x+1$

$\mathrm{solve}\left(f=0\&comma;x\right)$

Error, invalid input: solve expects its 1st argument, eqs, to be of type {`and`, `not`, `or`, rtable, algebraic, relation(algebraic), relation({rtable, algebraic}), {list, set}({`and`, `not`, `or`, algebraic, relation(algebraic)})}, but received (y = x^2+2*x+1) = 0

$\mathrm{solve}\left(\mathrm{rhs}\left(f\right)=0\&comma;x\right)$

$\mathrm{-1},\mathrm{-1}$