正負數!!救我ar!!!

1)(-5x)+7x
=-5x+7x
=2x
2)(-2a)+(-15a)
=-2a-15a
=-17a
3)(-8份之5a)+(-4份之0a)
=(5a/-8)-0a/4
=-5a/8-0
=-5a/8(又可寫成-0.625a)

1)
(-5x) + 7x
= 7x - 5x
= 2x
______________________

2)
(-2a) + (-15a)
= -2a - 15a
= -17a
______________________

3)
你是說 5a/(-8) + a/(-4)，而不是 5a/(-8) + (0a)/(-4) 嗎？如果是的話，那麼：

5a/(-8) + a/(-4)
= -5a/8 + (2/2)(-a/4)
= -5a/8 - 2a/8
= -7a/8

1.(-5x)+7X
=-5x+7x
=2x

2.(-2a)+(-15a)
=-2a-15a
=-17a

3.(5a/-8)+(a/4) <----你條式寫得唔好，a前面唔會係0，係1
=5a/-8+2a/-8
=5a+2a/-8
=7a/-8

1. (-5x)+7x
= -5x+7x
= (-5+7)(x)
= 2x

2. (-2a)+(-15a)
= -2a -15a
= (-2 -15)(a)
= -17a

3. (-8份之5a)+(-4份之0a)
= -5a/8 +( -0/4)
= -5a/8 +0
= -5a/8

1.(-5x)+7x
=-5x+7x
=2x
2.)(-2a)+(-15a)
=-2a-15a
=-17a
3.(-8份之5a)+(-4份之0a)
=-8份之5a-4份之0a
**咩叫0a