X^2-14x+45=x^2-14x+45+4-4=(x^2-14x+49)-4=(x-7)^2-2^2=(x-7-2)(x-7+2)=(x-9)(x-5)
√((3,02-2,98)/√(40²-32²))=
=√((3,02+2,98)(3,02-2,98)/√(40+32)(40-32))=
=√((6*0,04/√(72*8))=√(6*0,04/24)=√0,01=0,1.
√(66√(50²-40²)/√(44²+33²))=√(66√((50+40)(50-40))/√3025)=
=√(66√900/55)=√(66*30/55)=√(180/5)=√36=6.