1.16-49a^2=(4-7a)(4+7a)
4x^2-9a^2=(2x-3a)(2x+3a)
1-4b^2=(1-2b)(1+2b)
100-36a^2=(10-6a)(10+6a)
2. (m-n)^2-p^2=m^2-2mn+n^2-p^2=(m^2-2mn)+(n^2-p^2)=m(m-2n)+(n-p)(n+p)
4a^2-(a+3b)^2=4a^2-a^2-6ab-9b^2=3a^2-6ab+9b^2=3(a^2-2ab+3b^2)
3. m^2+n^2 , если m-n=3, а mn=28
m=3+n
(3+n)*n=28
3n+n^2-28=0
n^2+3n-28=0
D=9-4*(-28)=121
n1=-1+11/2=5
n2=-1-11/2=-6
m1=3+5=8
m2=3-6=-3
m^2+n^2=8^2+5^2=64+25=89
m^2+n^2=(-6)^2+(-3)^2=36+9=45
Ответ:89,45.