Math

QuestionFind numbers to exclude from the domain of these rational expressions: 1. 7x3\frac{7}{x-3}, 2. 13x+9\frac{13}{x+9}, 3. x+5x225\frac{x+5}{x^{2}-25}, 4. x+7x249\frac{x+7}{x^{2}-49}, 5. x1x2+11x+10\frac{x-1}{x^{2}+11 x+10}, 6. x3x2+4x45\frac{x-3}{x^{2}+4 x-45}.

Studdy Solution

STEP 1

Assumptions1. We are dealing with rational expressions. . A rational expression is undefined when the denominator is zero.
3. We need to find the values of x that make the denominator zero, as these values must be excluded from the domain.

STEP 2

For the first rational expression 7x\frac{7}{x-}, we set the denominator equal to zero and solve for x.
x=0x - =0

STEP 3

olve the equation to find the value of x that makes the denominator zero.
x=3x =3So,3 must be excluded from the domain of the first rational expression.

STEP 4

For the second rational expression 13x+9\frac{13}{x+9}, we set the denominator equal to zero and solve for x.
x+9=0x +9 =0

STEP 5

olve the equation to find the value of x that makes the denominator zero.
x=9x = -9So, -9 must be excluded from the domain of the second rational expression.

STEP 6

For the third rational expression x+5x225\frac{x+5}{x^{2}-25}, we set the denominator equal to zero and solve for x.
x225=0x^{2} -25 =0

STEP 7

This is a quadratic equation, so we can factor it to find the values of x.
(x5)(x+5)=0(x -5)(x +5) =0

STEP 8

Setting each factor equal to zero gives the solutions.
x5=0x=5x -5 =0 \Rightarrow x =5x+5=0x=5x +5 =0 \Rightarrow x = -5So,5 and -5 must be excluded from the domain of the third rational expression.

STEP 9

For the fourth rational expression x+7x249\frac{x+7}{x^{2}-49}, we set the denominator equal to zero and solve for x.
x249=x^{2} -49 =

STEP 10

This is a quadratic equation, so we can factor it to find the values of x.
(x7)(x+7)=0(x -7)(x +7) =0

STEP 11

Setting each factor equal to zero gives the solutions.
x7=0x=7x -7 =0 \Rightarrow x =7x+7=0x=7x +7 =0 \Rightarrow x = -7So,7 and -7 must be excluded from the domain of the fourth rational expression.

STEP 12

For the fifth rational expression xx2+11x+10\frac{x-}{x^{2}+11x+10}, we set the denominator equal to zero and solve for x.
x2+11x+10=0x^{2} +11x +10 =0

STEP 13

This is a quadratic equation, so we can factor it to find the values of x.
(x+)(x+10)=0(x +)(x +10) =0

STEP 14

Setting each factor equal to zero gives the solutions.
x+=0x=x + =0 \Rightarrow x = -x+10=0x=10x +10 =0 \Rightarrow x = -10So, - and -10 must be excluded from the domain of the fifth rational expression.

STEP 15

For the sixth rational expression x3x2+4x45\frac{x-3}{x^{2}+4x-45}, we set the denominator equal to zero and solve for x.
x2+4x45=0x^{2} +4x -45 =0

STEP 16

This is a quadratic equation, so we can factor it to find the values of x.
(x5)(x+9)=0(x -5)(x +9) =0

STEP 17

Setting each factor equal to zero gives the solutions.
x5=0x=5x -5 =0 \Rightarrow x =5x+9=0x=9x +9 =0 \Rightarrow x = -9So,5 and -9 must be excluded from the domain of the sixth rational expression.

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