Kunci Jawaban Matematika

 Kelas 7 Jawaban :

1 ) 

a ) 2 (-2a + 7b) – (a + 4b)

= (-4a + 14b) – (a + 4b)

= – 4a – a + 14b – 4b

= – 5a + 10b

b ) 6(2a2 + 3a2b – 7ab) – 4a(5a – 2b + 5ab)

= (12a2 + 18a2b – 42ab) – (20a2 – 8ab + 20a2b) 

= 12a2 – 20a2 + 18a2b – 20a2b – 42ab + 8ab

= –8a2 – 2a2b – 34ab

2 ) 

a ) 2(ab + b – 3c) – 2(c – b + 6a)

= (2ab + 2b – 6c) – (2c – 2b + 12a)

= 2ab + 2b + 2b – 6c – 2c + 12a

= 2ab + 4b – 8c + 12a

b ) 4b2(3a – 4b – c) – 5a2(a – b – c)

= (12ab2 – 16b3 – 4b2c) – (5a3 – 5a2b – 5a2 c)

= 12ab2 – 16b3 –  4b2c – 5a3 + 5a2b + 5a2c

Kelas 9

 1.

2. 

3. x’ = 2 – x ó x = 2 – x’

y’ = -4 – y ó y = -4 – y’

x = 2 – 3 = -1

y = -4 – 5 = -9 Jadi A(-1, -9)

4. (x, y) ó (2a – x, y)

x’ = 2(-1) – x ó x’ = -2 – x

y’ = y

2(-2 – x’) – y’ = 5

-y – 2x’ – y’ = 5

2x’ + y’ + 9 = 0 Jadi bayangan 2x + y + 9 = 0

5. Pembahasan :

(x, y) ó (-y, -x)

x’ = -y , y’ = -x

2(-y’) – (-x’) = 5

x’ – 2y’ – 5 = 0 Jadi bayangan x – 2y – 5 = 0