sweetjennifer1237
Answered

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Bonjour !
Please solve My maths problem.
If X = 2y +6, then find the value of x³ - 8y³ - 36xy -216.
Hint - answer is 0
Kindly Show steps
I desperately need help with this question.
Correct person will be appreciated and brainlist will be awarded
Irellevant answer won't be tolerated and will be reported immediately.
Thank you in. advance !
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Sagot :

alexanderorangeguy

y = 1

Step-by-step explanation:

X = 2y + 6

X³ - 8y³ - 36xy - 216 = 0

(subsitute)

(2y + 6)³ - 8y³ - 36(2y + 6)y -216 = 0

(concentrate on first part)

(2y + 6)(2y + 6)(2y + 6)

(4y² + 12y + 12y + 36)(2y + 6)

(4y² + 24y + 36)(2y + 6)

8y³ + 24y² + 48y² + 144y + 72y + 216

(back to full equation)

8y³ + 72y² + 216y + 216 - 8y³ - 36(2y + 6)y - 216 = 0

(factor the last part)

-36(2y + 6)y

y(-72y - 216)

-72y² - 216y

(back to main equation)

8y³ + 72y² + 216y + 216 - 8y³ - 72y² - 216y - 216 = 0

(start to cancel out)

8y³ and -8y³ cancel

72y² + 216y + 216 - 72y² - 216y - 216 = 0

72y² and -72y² cancel

216y + 216 - 216y - 216 = 0

216y and -216y cancel

216 - 216 = 0

those cancel

0y = 0

add 1 to both sides

y = 1.

(I hope this helped)

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