Question

43*42,Find the value using expansion formula.

Answer 1

Hey there!

43 * 42

= ( 40 + 3 ) ( 40 + 2 )

= 40² + ( 2 + 3 ) 40 + 2 × 3

= 1600 + 200 + 6

= 1806

Here, We have used simplification using identities.

( x - a) ( x - b)

= x ( x - b ) - a ( x - b)

= x² -ax -bx + ab

= x² - (a + b) x + ab.

That is, ( x - a) ( x - b) = x² - (a + b) x + ab.

Hope helped

Answer 2

BONJOUR,
❤ ❤ ❤ ❤

$43 \times 42 \\ (40 + 3)(40 + 2) \\ 40(40 + 3) + 2(40 + 3) \\ 1600 + 120 + 80 + 6 \\ = 1780 + 86 \\ = 1806$