Question

Urgent!!
Ex 21,22,23

Answer 1

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Answer 2

21. A(-2;1)∈Gf ⇔
f(-2)=1
f(-2)=-2 ·3+7=-6+7=1
1=1 ⇒f(-2)=1 ⇒A(-2;1)∈Gf ;
22. A(1/2;2)∈Gf ⇔
f(1/2)=2
f(1/2)=3+a
⇔3+a=2 ⇒a=-1 ;
23. A(3;-1)∈Gf ⇔
f(3)=-1 
f(3)=3a+2
⇔3a+2=-1 ⇒3a=-3 ⇒a=-1 ;