Datrys (7a-4b+3c-18)-(8a+7b-8c+6)+5(2a-b+2c-3)=

$$( 7 a - 4 b + 3 c - 18 ) - ( 8 a + 7 b - 8 c + 6 ) + 5 ( 2 a - b + 2 c - 3 ) =$$

Enrhifo

$$9a-16b+21c-39$$

Camau Ateb

I ddod o hyd i wrthwyneb 8a+7b-8c+6, dewch o hyd i wrthwyneb pob term.

$$7a-4b+3c-18-8a-7b-\left(-8c\right)-6+5\left(2a-b+2c-3\right)$$

Gwrthwyneb -8c yw 8c.

$$7a-4b+3c-18-8a-7b+8c-6+5\left(2a-b+2c-3\right)$$

Cyfuno 7a a -8a i gael -a.

$$-a-4b+3c-18-7b+8c-6+5\left(2a-b+2c-3\right)$$

Cyfuno -4b a -7b i gael -11b.

$$-a-11b+3c-18+8c-6+5\left(2a-b+2c-3\right)$$

Cyfuno 3c a 8c i gael 11c.

$$-a-11b+11c-18-6+5\left(2a-b+2c-3\right)$$

Tynnu 6 o -18 i gael -24.

$$-a-11b+11c-24+5\left(2a-b+2c-3\right)$$

Defnyddio’r briodwedd ddosbarthu i luosi 5 â 2a-b+2c-3.

$$-a-11b+11c-24+10a-5b+10c-15$$

Cyfuno -a a 10a i gael 9a.

$$9a-11b+11c-24-5b+10c-15$$

Cyfuno -11b a -5b i gael -16b.

$$9a-16b+11c-24+10c-15$$

Cyfuno 11c a 10c i gael 21c.

$$9a-16b+21c-24-15$$

Tynnu 15 o -24 i gael -39.

$$9a-16b+21c-39$$

Ehangu

$$9a-16b+21c-39$$

Camau Ateb

I ddod o hyd i wrthwyneb 8a+7b-8c+6, dewch o hyd i wrthwyneb pob term.

$$7a-4b+3c-18-8a-7b-\left(-8c\right)-6+5\left(2a-b+2c-3\right)$$

Gwrthwyneb -8c yw 8c.

$$7a-4b+3c-18-8a-7b+8c-6+5\left(2a-b+2c-3\right)$$

Cyfuno 7a a -8a i gael -a.

$$-a-4b+3c-18-7b+8c-6+5\left(2a-b+2c-3\right)$$

Cyfuno -4b a -7b i gael -11b.

$$-a-11b+3c-18+8c-6+5\left(2a-b+2c-3\right)$$

Cyfuno 3c a 8c i gael 11c.

$$-a-11b+11c-18-6+5\left(2a-b+2c-3\right)$$

Tynnu 6 o -18 i gael -24.

$$-a-11b+11c-24+5\left(2a-b+2c-3\right)$$

Defnyddio’r briodwedd ddosbarthu i luosi 5 â 2a-b+2c-3.

$$-a-11b+11c-24+10a-5b+10c-15$$

Cyfuno -a a 10a i gael 9a.

$$9a-11b+11c-24-5b+10c-15$$

Cyfuno -11b a -5b i gael -16b.

$$9a-16b+11c-24+10c-15$$

Cyfuno 11c a 10c i gael 21c.

$$9a-16b+21c-24-15$$

Tynnu 15 o -24 i gael -39.

$$9a-16b+21c-39$$