=11/20

chúng Ta có                          x2−y2−6x+9x2-y2-6x+9

                                        =(x2−6x+9)−y2=(x2-6x+9)-y2

                                              =(x−3)2−y2=(x-3)2-y2

                                              =(x−3−y)(x−3+y)=(x-3-y)(x-3+y)

                                              ⇒a=1;b=1;c=−3⇒a=1;b=1;c=-3

                                                ⇒a+b+c=1+1−3⇒a+b+c=1+1-3

                                              ⇒a+b+c=−1

1 pandas don't live in australia

they live in china

2 fish don't swim in the air

they swim in the sea

3 bananas don't grow in cold countries

they grom in hot countries

4 kanguroos don't live in china

they live in australia

5 peanuts don't grow on trees

they grow in the ground

6 penguins don't live in hot countries

they live in cold countries

A

TK

3/4+x=17/4

x=17/4-3/4

x=14/4=7/2

x-3/5=5/25

x-3/5=1/5

x=1/5+3/5

x=4/5