Chapter 11 - 11.5 - The Binomial Theorem - 11.5 Exercises - Page 813: 42

$-35000x^4z^3$

According to the Binomial Theorem we can obtain the $r+1$th term of the expansion of the binomial $(x+y)^n$ by the formula $_nC_rx^{n-r}y^r$. Hence here it is: (by plugging in $n=7,r=3$ and $x,-10z$): $_{7}C_3(x)^{7-3}(-10z)^3=35x^4\cdot-1000z^3=-35000x^4z^3$