Ab-ac+5b-5c = (ab-ac) + (5b-5c) = a(b-c) + 5 (b-c) = (b-c) (a+5)
tex] = [tex] 25a^{2} - ( 4a^{2} - 32a+ 64)= 25a^{2}- 4a^{2} + 32a - 64" alt=" 25a^{2} - (2a-8)^{2} tex] = [tex] 25a^{2} - ( 4a^{2} - 32a+ 64)= 25a^{2}- 4a^{2} + 32a - 64" align="absmiddle" class="latex-formula"> =