Question

answer if u know.......... If not then don't answer
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Answer 1

Answer:

(5mn+4m)²-(5mn-4m)²=80m²n.

LHS.

(5mn+4m)².

By using formula (a+b)²=a²+b²+2ab where a=5mn & b=4m.

(5mn+4m)²=(5mn)²+(4m)²+2(5mn)(4m).

=25m²n²+16m²+40m²n.

(5mn-4m)².

By using formula (a-b)²=a²+b²-2ab where a=5mn & b=4m.

(5mn-4m)²=(5mn)²+(4m)²-2(5mn)(4m).

=25m²n²+16m²-40m²n.

(5mn+4m)²-(5mn-4m)²=(25m²n²+16m²+40m²n)-(25m²n²+16m²-40m²n).

(Because (5mn+4m)²=25m²n²+16m²+40m²n & (5mn-4m)²=25m²n²+16m²-40m²n).

25m²n²+16m²+40m²n-25m²n²-16m²+40m²n.

(Because -×+=- & -×-=+).

40m²n+40m²n.

(Because +×-=- so, 25m²n²-25m²n² & 16m²-16m² will cancel i.e., It will be zero(0)).

80m²n.

RHS.

LHS=RHS.