Mathematics: How to multiply rational expressions? pls help me...

the ans is (A) . -2x^3 + 8x^2 - 3....

How to multiply rational expressions? pls help - id8311017, amandasantiago2001

AleciaCassidy

05.02.2022

Point :

A × B = B × A

Ex)

$\frac{1}{2} \times \frac{3}{4} = \frac{3}{4} \times \frac{1}{2} = \frac{3}{2} \times \frac{1}{4}$

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a )

$\frac{12 {a}^{2} }{25 {b}^{3} } \times \frac{5b}{4 {a}^{4} } = \frac{12 {a}^{2} }{4 {a}^{4} } \times \frac{5b}{25 {b}^{3} } = \\$

$\frac{4 {a}^{2} \times 3 }{4 {a}^{2} \times {a}^{2} } \times \frac{5b}{5b \times 5 {b}^{2} } = \\$

$\frac{3}{ {a}^{2} } \times \frac{1}{5 {b}^{2} } = \frac{3}{5 {a}^{2} {b}^{2} } \\$

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b )

$\frac{ {x}^{2} - 2x - 15 }{ {x}^{2} - 9 } \times \frac{ {x}^{2 } - 6x + 9 }{4x - 12} = \\$

$\frac{(x - 5)(x + 3)}{(x - 3)(x + 3)} \times \frac{(x - 3)(x - 3) }{4(x - 3)} = \\$

$\frac{(x - 5)}{(x - 3)} \times \frac{(x - 3)}{4} = \\$

$\frac{(x - 3)(x - 5)}{(x - 3) \: \: \: \times \: \: 4} = \frac{x - 5}{4} \\$

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And we're done.....♥️♥️♥️♥️♥️

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