1) 1-a^2+10ab-25b^2 = 1-(a^2-10ab+25 b^2) = 1- (a-5b)^2= (1+a-5b) (1-a+5b)
2) m^2+2mn+n^2-mp-np= (m+n)^2 - p(m+n) = (m+n) (m+n-p)
1) 1-a^2+10ab-25b^2 = 1-(a^2-10ab+25 b^2) = 1- (a-5b)^2= (1+a-5b) (1-a+5b)
2) m^2+2mn+n^2-mp-np= (m+n)^2 - p(m+n) = (m+n) (m+n-p)