task/29449180 ----------------------
Доказать ,что тождественные равны выражения :
1/ (6x+10) -1 / (9x -15) + 5 / (9x²-25 ) и 1/6(3x-5). * * * A² -B² = (A - B)(A+B) * * *
1/ 2(3x+5) -1 / 3(3x -5) + 5 / (3x-5)(3x+5) =( 3(3x -5) - 2(3x+5 + 5*6 )/6 (3x-5)(3x+5) =( 9x -15) - 6x - 10 + 30 ) /6 (3x-5)(3x+5) = (3x+5) /6(3x-5)(3x+5) = 1/6(3x+5) .
1 / (6х+10) - 1 / (9х-15) + 5 / (9х²-25) = 1 / 6*(3х-5),
1 / 2*(3х+5) - 1 / 3*(3х-5) + 5 / (3х-5)(3х+5) = 1 / 6*(3х-5),
3*(3х-5) / 6*(3х-5)(3х+5) - 2*(3х+5) / 6*(3х-5)(3х+5) + 5*6 / 6*(3х-5)(3х+5) =
= 1 / 6*(3х-5),
(9х-15 - 6х-10 + 30) / 6*(3х-5)(3х+5) = 1 / 6*(3х-5),
(3х+5) / 6*(3х-5)(3х+5) = 1 / 6*(3х-5),
1 / 6*(3х-5) = 1 / 6*(3х-5)
тождество выражений доказано
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Answers & Comments
task/29449180 ----------------------
Доказать ,что тождественные равны выражения :
1/ (6x+10) -1 / (9x -15) + 5 / (9x²-25 ) и 1/6(3x-5). * * * A² -B² = (A - B)(A+B) * * *
1/ 2(3x+5) -1 / 3(3x -5) + 5 / (3x-5)(3x+5) =( 3(3x -5) - 2(3x+5 + 5*6 )/6 (3x-5)(3x+5) =( 9x -15) - 6x - 10 + 30 ) /6 (3x-5)(3x+5) = (3x+5) /6(3x-5)(3x+5) = 1/6(3x+5) .
Verified answer
1 / (6х+10) - 1 / (9х-15) + 5 / (9х²-25) = 1 / 6*(3х-5),
1 / 2*(3х+5) - 1 / 3*(3х-5) + 5 / (3х-5)(3х+5) = 1 / 6*(3х-5),
3*(3х-5) / 6*(3х-5)(3х+5) - 2*(3х+5) / 6*(3х-5)(3х+5) + 5*6 / 6*(3х-5)(3х+5) =
= 1 / 6*(3х-5),
(9х-15 - 6х-10 + 30) / 6*(3х-5)(3х+5) = 1 / 6*(3х-5),
(3х+5) / 6*(3х-5)(3х+5) = 1 / 6*(3х-5),
1 / 6*(3х-5) = 1 / 6*(3х-5)
тождество выражений доказано