Question

Hello there.... :)
please help me out with this:
If a−b=4 and ab=45, find the value of
$a^3-b^3$
NO SPAM... :)

Answer 1

Answer:

(a) ^3+(b) ^3-2XaXb=(4)^3

a^3b^3-2ab=48

a^3b^3=48+2ab (Putting the value of ab)

a^3b^3=48+2X45

a^3b^3=48+90

a^3b^3=138

Hope my answer is correct.

Answer 2

$\large { \underline{ \bf \red{Question:- }}}$

If a−b=4 and ab=45, find the value of a^3-b^3

$\large { \underline{ \bf \purple{Solution:- }}}$

ᴀ−ʙ=4

ᴀʙ=45

ᴀ3−ʙ3=(ᴀ−ʙ)(ᴀ2+ʙ2+ᴀʙ)

=(ᴀ−ʙ)(ᴀ2+ʙ2−2ᴀʙ+2ᴀʙ+ᴀʙ)

=(ᴀ−ʙ)((ᴀ−ʙ)2+3ᴀʙ)

=4(16+3×45)

=4(16+135)

=4×151

=604

$\large { \underline{ \bf \pink{Therefore:- }}}$

$604 \: is \: the \: Correct \: Answer$