Question

a-b=7 and a2+b2=85,find a3=b3

Answer 1

Hey !!! ^_^


Here is your answer

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a - b = 7

So,

a = b + 7


a² + b² = 85


(b + 7)² + b² = 85

b² + 49 + 14b + b² = 85

2b² + 14b - 36 = 0

b² + 7b - 18 = 0

b² + 9b - 2b - 18 = 0

b( b + 9) - 2 ( b + 9) = 0

(b - 2)(b + 9) = 0

b = 2 ...✔✔...or b = - 9 ❎

b = 2

a = b + 7

a = 9

.......

a³ - b³

9³ - 2³

729 - 8

721 .....ans


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Answer 2

HeÿA ❗❗

Solution ---->>

a - b = 7

a = b + 7

a² + b² = 85

(b + 7)² + b² = 85

on solving we get --->

2b² + 14b - 36 = 0

b² + 7b - 18 = 0

b² + 9b -2b - 18=0

b (b+9) -2 (b+9) = 0

(b-2) (b+9) = 0

By Zero property we get

if b-2=0
Then b = 2

if b+9=0
Then b = -9

a = b+ 7

a = 2+7

a=9

a³-b³

9³ - 2³

729 - 8

=721

Answer =721

HöPe ïT hèLps uhh ❤❤❤❗❗❗