Question

数学题x-15/x^2-9-2x/9-x^2÷x/3+x

Answer 1

原式=[ (x-15)/(x²-9) ]- [ 2x/(9-x²) ]÷[ x/(3+x) ]

=[ (x-15)/(x²-9) ]+[ 2x/(x²-9) ]×[ (x+3)/x ]

=[ (x-15)/(x²-9)] +[ 2(x+3)/(x²-9) ]

=[ (x-15)+2(x+3) ]/(x²-9)

=(x-15+2x+6)/(x²-9)

=(3x-9)/(x²-9)

=3(x-3)/[(x-3)(x+3)]

=3/(x+3)