We study the joint distribution of values of a pair consisting of a quadratic form
${\mathbf q}$
and a linear form
${\mathbf l}$
over the set of integral vectors, a problem initiated by Dani and Margulis [Orbit closures of generic unipotent flows on homogeneous spaces of
$\mathrm{SL}_3(\mathbb{R})$
. Math. Ann.286 (1990), 101β128]. In the spirit of the celebrated theorem of Eskin, Margulis and Mozes on the quantitative version of the Oppenheim conjecture, we show that if
$n \ge 5$
, then under the assumptions that for every
$(\alpha , \beta ) \in {\mathbb {R}}^2 \setminus \{ (0,0) \}$
, the form
$\alpha {\mathbf q} + \beta {\mathbf l}^2$
is irrational and that the signature of the restriction of
${\mathbf q}$
to the kernel of
${\mathbf l}$
is
$(p, n-1-p)$
, where
${3\le p\le n-2}$
, the number of vectors
$v \in {\mathbb {Z}}^n$
for which
$\|v\| < T$
,
$a < {\mathbf q}(v) < b$
and
$c< {\mathbf l}(v) < d$
is asymptotically
$ C({\mathbf q}, {\mathbf l})(d-c)(b-a)T^{n-3}$
as
$T \to \infty $
, where
$C({\mathbf q}, {\mathbf l})$
only depends on
${\mathbf q}$
and
${\mathbf l}$
. The density of the set of joint values of
$({\mathbf q}, {\mathbf l})$
under the same assumptions is shown by Gorodnik [Oppenheim conjecture for pairs consisting of a linear form and a quadratic form. Trans. Amer. Math. Soc.356(11) (2004), 4447β4463].