Question

10×(4+5)=10×___+10×__​

Answer 1

Answer:

$\to \: \sf \: 10 \times (4 + 5) = 10 \times... + 10 \times ... \\ \\ \to\: \sf \: 10 \times (4 + 5) = 10 \times 4 + 10 \times 5 \\ \\ \sf\to \: \: 10 \times( 4 + 5) = 40 + 50 \\ \\ \to \: \sf \: 10 \times (4 + 5) = 90 \\ \\ \to \bf \: = 90$

Some important identities:

$\bullet \sf \: (x + y)(u + v) = xu + xv + yu + yv$

$\bullet\sf \: \: (y + 1)(x + 1) = yx + y + x + 1$

$\bullet\sf \: ( {x + y})^{2} = {x}^{2} + {y}^{2} + 2xy$

$\bullet\sf \: (x - y)(u - v) = xu - xv - yu + yv$

$\bullet\sf \: ( {x - y)}^{2} = {x}^{2} + {y}^{2} - 2xy$

$\sf\bullet \: ( {x + y)}^{2} - ( {x - y)}^{2} = ( {x}^{2} + {y}^{2} + 2xy) - ({x}^{2} + {y}^{2} - 2xy)$

$\bullet\sf \: (x + y)(u - v) = xu - xv + yu - yv$

$\bullet\sf \: (x +y )(x - y) = {x}^{2} - {y}^{2}$

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