begin{align}
 a &= b + left(begin{array}{cc} c & x \ c & x end{array}right)\
 d &= e + f + left(begin{array}{cc} ggg & x \ ggg & x end{array}right)
end{align}

documentclass[a4paper, 11pt]{book}
usepackage[utf8]{inputenc}
usepackage{fourier}

usepackage{mathtools}

begin{document}

begin{alignat}{2}
 a &= b &+ begin{pmatrix}c & x \ c & x end{pmatrix} & \
 d &= e & + f + begin{pmatrix}ggg & x \ ggg & x end{pmatrix} &
 end{alignat}

end{document}