16x^2=0
x^2=0
x=0
Ответ: x=0
Решение7/7-х. + х^2+49/х^2-49 при х= - 14.
7/(7 - х). + (х^2 + 49)/(х^2 - 49) = 7 / (7 - x) - (x² + 49) / [(7 - x)*(7 + x)] == [7*(7 + x) - x² + 49] / [(7 - x)*(7 + x)] = [49 + 7x - x² - 49] / [(7 - x)*(7 + x)] == [x*(7 - x)] / [(7 - x)*(7 + x)] = x / (7 + x)при х= - 14. - 14 / (7 - 14) = - 14/(-7) = 2
![\frac{ (a+b)^{2}- (ab+1)^{2} }{( a^{2} -1)( b^{2} -1)} = \frac{( a^{2}+2ab+ b^{2})-( a^{2} b^{2} +2ab+1)}{( a^{2}-1)( b^{2} -1) } = \frac{ a^{2}+ b^{2} - a^{2}b^{2}-1 }{( a^{2} -1)(b^{2} -1)} =](https://tex.z-dn.net/?f=+%5Cfrac%7B+%28a%2Bb%29%5E%7B2%7D-+%28ab%2B1%29%5E%7B2%7D++%7D%7B%28+a%5E%7B2%7D+-1%29%28+b%5E%7B2%7D+-1%29%7D+%3D+%5Cfrac%7B%28+a%5E%7B2%7D%2B2ab%2B+b%5E%7B2%7D%29-%28+a%5E%7B2%7D++b%5E%7B2%7D+%2B2ab%2B1%29%7D%7B%28+a%5E%7B2%7D-1%29%28+b%5E%7B2%7D+-1%29+%7D+%3D++%5Cfrac%7B+a%5E%7B2%7D%2B+b%5E%7B2%7D+-+a%5E%7B2%7Db%5E%7B2%7D-1+%7D%7B%28+a%5E%7B2%7D+-1%29%28b%5E%7B2%7D+-1%29%7D+%3D+)
![\frac{( a^{2} -1)-( a^{2}b^{2} - b^{2} )}{( a^{2} -1)(b^{2} -1)} = \frac{( a^{2} -1)- b^{2} ( a^{2} -1)}{( a^{2} -1)( b^{2} -1)} = \frac{( a^{2} -1)(1- b^{2} )}{( a^{2} -1)( b^{2} -1)} = \frac{1- b^{2} }{ b^{2} -1} = -\frac{b^{2} -1}{b^{2} -1} =-1](https://tex.z-dn.net/?f=+%5Cfrac%7B%28+a%5E%7B2%7D+-1%29-%28+a%5E%7B2%7Db%5E%7B2%7D+-+b%5E%7B2%7D+%29%7D%7B%28+a%5E%7B2%7D+-1%29%28b%5E%7B2%7D+-1%29%7D+%3D+%5Cfrac%7B%28+a%5E%7B2%7D+-1%29-+b%5E%7B2%7D+%28+a%5E%7B2%7D+-1%29%7D%7B%28+a%5E%7B2%7D+-1%29%28+b%5E%7B2%7D+-1%29%7D+%3D+%5Cfrac%7B%28+a%5E%7B2%7D+-1%29%281-+b%5E%7B2%7D+%29%7D%7B%28+a%5E%7B2%7D+-1%29%28+b%5E%7B2%7D+-1%29%7D+%3D+%5Cfrac%7B1-+b%5E%7B2%7D+%7D%7B+b%5E%7B2%7D+-1%7D+%3D+-%5Cfrac%7Bb%5E%7B2%7D+-1%7D%7Bb%5E%7B2%7D+-1%7D+%3D-1)
Ответ: - 1 при любых значениях переменных a и b,