Rational expressions and least common multiple

Find all numbers for which the rational expression is undefined.
-15/23z

Find all numbers for which the rational expression is undefined.
(t^(3 )-6t)/(t^2-25)

Simplify by removing factor of 1.
(〖80v〗^( 8 ) y^9)/(〖50v〗^(4 ) y^6 ) (The simplified form is)

Simplify by removing factor of 1.
(r^(2 )-16)/(r^(2 )-8r+16)

Simplify by removing factor of 1
(〖21v〗^(2 )-189)/(〖49v〗^(2 )-441)

Multiply and simplify
〖7b〗^(7 )/〖11v〗^4 ∙ 〖121v〗^8/49b

Multiply and simplify
(w^(2 )-4w-45)/(w^(2 )-10w+25 ) ∙ (w-5)/(w-9) (Simplify your answer)

Divide and simplify
f/b^2 ÷ f^2/b^3

Divide and simplify
(x^(2 )-36)/x ÷ (x-6)/(x+7) (Type a fraction. Leave your answer in factored form)

Divide and simplify
(x^(2 )-1)/(49x+49) ÷ (x-1)/7 (Type a fraction)

Divide and simplify
(z^(2 )+4z)/(z^(2 )+2z-8) ÷ z/(z+2) (Type a fraction)

Find the LCM of
〖10x〗^4, 〖50x〗^6

Find the LCM of
q^(2 )-49,q^(2 )+12q+35

Find the LCM of
w^(3 )+ 〖10w〗^(2 )+25w, w^(2 )-10w

〖9y〗^2+45y,〖 3y〗^2+24y+45

Add
6/(8+z) +1/(8+z)

Add. Simplify if possible
(x^(2 )+13x)/(x^(2 )-8x) +(x^(2 )-6x)/(x^(2 )-8x)

Add. Simplify if possible
7/〖25z〗^3 +1/〖35z〗^2

Add.
6/(v-8) +6/(v-8) (Simplify your answer)

Add. Simplify if possible
6x/(x^(2 )-9) +x/(x-3)

Add and simplify if possible
(w+1)/w +w/(w+1)

Subtract and simplify if possible
(z-9)/z-(3z-17)/7z (Simplify your answer. Use integers or fraction for any numbers in the expression)

3/(〖7s〗^(2 )-7s) -7/(7s-7) ((Simplify your answer. Use integers or fraction for any numbers in the expression)

Subtract. Simplify by removing a factor of 1 when possible
12bc/b^(2 -c^2 ) - (b-c)/(b+c)

Subtract. Simplify if possible
(4-z)/(z-2)-(2z-5)/(2-z) (Simplify your answer)

Perform the indicated operation and simplify
(x-2)/(x-4)-(x+1)/(x+4)+(x-20)/(x^(2 )-16)

Simplifying the expression
(a²-1)/(a-1)-a

Simplify
((x^2 - 1) / (x - 1)) - 1