Whakaoti i te (4x-x)(7y+4x)-(2y+8x)(2y+5x)

$$(4x-x)(7y+4x)-(2y+8x)(2y+5x)$$

Aromātai

$$-28x^{2}-5xy-4y^{2}$$

Ngā Upane Otinga

Pahekotia te 4x me -x, ka 3x.

$$3x\left(7y+4x\right)-\left(2y+8x\right)\left(2y+5x\right)$$

Whakamahia te āhuatanga tohatoha hei whakarea te 3x ki te 7y+4x.

$$21xy+12x^{2}-\left(2y+8x\right)\left(2y+5x\right)$$

Me hoatu te āhuatanga tohatoha mā te whakarea ia tau o 2y+8x ki ia tau o 2y+5x.

$$21xy+12x^{2}-\left(4y^{2}+10yx+16xy+40x^{2}\right)$$

Pahekotia te 10yx me 16xy, ka 26yx.

$$21xy+12x^{2}-\left(4y^{2}+26yx+40x^{2}\right)$$

Hei kimi i te tauaro o 4y^{2}+26yx+40x^{2}, kimihia te tauaro o ia taurangi.

$$21xy+12x^{2}-4y^{2}-26yx-40x^{2}$$

Pahekotia te 21xy me -26yx, ka -5xy.

$$-5xy+12x^{2}-4y^{2}-40x^{2}$$

Pahekotia te 12x^{2} me -40x^{2}, ka -28x^{2}.

$$-5xy-28x^{2}-4y^{2}$$

Whakaroha

$$-28x^{2}-5xy-4y^{2}$$

Ngā Upane Otinga

Pahekotia te 4x me -x, ka 3x.

$$3x\left(7y+4x\right)-\left(2y+8x\right)\left(2y+5x\right)$$

Whakamahia te āhuatanga tohatoha hei whakarea te 3x ki te 7y+4x.

$$21xy+12x^{2}-\left(2y+8x\right)\left(2y+5x\right)$$

Me hoatu te āhuatanga tohatoha mā te whakarea ia tau o 2y+8x ki ia tau o 2y+5x.

$$21xy+12x^{2}-\left(4y^{2}+10yx+16xy+40x^{2}\right)$$

Pahekotia te 10yx me 16xy, ka 26yx.

$$21xy+12x^{2}-\left(4y^{2}+26yx+40x^{2}\right)$$

Hei kimi i te tauaro o 4y^{2}+26yx+40x^{2}, kimihia te tauaro o ia taurangi.

$$21xy+12x^{2}-4y^{2}-26yx-40x^{2}$$

Pahekotia te 21xy me -26yx, ka -5xy.

$$-5xy+12x^{2}-4y^{2}-40x^{2}$$

Pahekotia te 12x^{2} me -40x^{2}, ka -28x^{2}.

$$-5xy-28x^{2}-4y^{2}$$