Question

Find The Value of- i) 27x ^3 - 27x ^y + 9xy ^2 - y ^3 if x= 2, y= 1 ; ii) x ^3 + 1/125x ^3 if x ^2 + 1/25x ^2= 8 3/5(mixed fraction) This questions are from the Chapter Expansions

Answer 1

27x³ + 8y³

= (3x)³ + (2y)³

a³ + b³ = (a + b)(a² - ab + b²)

Given,

3x + 2y = 12 and xy = 6

(3x)³ + (2y)³ = (3x + 2y) {(3x)² - (3x)(2y) + (2y)²}

= 12 {(3x)² - 6xy + (2y)²}

= 12 {(3x)²-6(6)+(2y)²}

= 12 {(3x)²+(2y)² - 36}

= 12 {(3x)² + (2y)² + 2(3x)(2y) - 2(3x)(2y) - 36}

= 12 {(3x+2y)² - 12xy - 36

= 12 {(12)²-12(6)-36}

= 12 {144-72-36}

= 12 {36}

= 432

Hope it helps...,

Answer 2

Answer:

,

Step-by-step explanation:

hope this picture of the answer helps you