\(a,\left(-7\right).\left(-7\right).\left(-7\right).\left(-7\right)\)
\(=\left(-7\right)^4=2401\)
\(b,\left(-3\right).\left(-3\right).\left(-3\right).\left(-4\right).\left(-4\right).\left(-4\right)\)
\(=\left(-3\right)^3.\left(-4\right)^3=12^3\)
\(c,4.9.25\)
\(=9.\left(4.25\right)=900=30^2\)
\(d,8.\left(-3\right)^3.\left(-125\right)\)
\(=\left(-3\right)^3.\left[\left( -125\right).8\right]\)
\(=\left(-3\right)^3.\left(-1000\right)\)
\(=\left(-3\right)^3.\left(-10\right)^3\)
\(=30^3\)