Question

anyone who can solve it for 50pts​

Answer 1

(a+b) (c-d) = ac - ad + bc - bd. [eq. 1]

(a-b) (c+d) = ac +ad - bc - bd. [eq. 2]

2(ac + bd) = 2ac + 2bd. [eq. 3]

now from eq 1, 2 & 3 we get

ac- ad + bc - bd + ac + ad - bc - bd + 2ac 2bd

== 2ac -2bd +2ac +2bd

== 4ac. ans

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Answer 2

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(a+b)(c-d)+(a-b)(c+d)+2(ac+bd)

a(c-d)+b(c-d)+a(c+d)-b(c+d)+2ac+2bd

ac -ad +bc -bd +ac +ad -bc -bd +2ac +2bd

[ad and bc cancelled with the same one]

Now,

The rest -

ac -bd -bd +ac +2ac +2bd

2ac +2ac

=4ac.

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