If a- b= 7 and (a)2 +(b)2 = 85 ,find (a)3 - (b)3.

1.	If a- b= 7 and (a)2 +(b)2 = 85 ,find (a)3 - (b)3.
Answer» a-b=7 ⇒a=7+b .....(i)a²+b²=85 ....(ii)Substitution of equation 1 to equation 2.(7+b)²+b² =8549+14b +b²+b² =852b²+14b-36 =0 b² +7b -18 =0\xa0(b+9)(b-2) =0b=-9 v b=2Find value of aa-b=7⇒if b=-9a-(-9)=7a =7-9 =-2⇒if b=2a-2=7a = 7+2 =9So value of a³ - b³ there are 2 options⇒if (a,b) = (-2,-9)a³-b³ = -2³ - (-9)³ = -8 +729 = 721⇒if (a,b) = (2,9)a³-b³ = 2³ - 9³ = 8-729 = -721

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