`x^{2}-y^{2}+14x+49`
`=(x^{2}+14x+49)-y^{2}`
`=(x+7)^{2}-y^{2}`
`=(x+7-y)(x+7+y)
\(=\left(x^2+14x+49\right)-y^2\\ =\left(x+7\right)^2-y^2\\ =\left(x+7-y\right)\left(x+y+7\right)\)
`= (x+7)^2 - y^2`
`= (x+y+7)(x+7-y)`
\(x^2-y^2+14x-49\)
\(=\left(x^2+2.7x+7.7\right)-y^2\)
\(=\left(x+7\right)^2-y^2\)
\(=\left(x-y+7\right)\left(x+y+7\right)\)