4.
f:R->R;f(x)=12x+8
M(m;11)
M∉Gf
f(m)≠11=>12m+8≠11<=>12m≠3=>m≠3/12=>m≠1/4
m∈R/{1/4}
5.
f:[1;a]->R
g:[b;10]->R
Df=Dg=>1=b si a=10
f(x)=cx+8
g(x)=6x+9-d
xf=xg=>cx=6x |:x=>c=6
8=9-d=>d=9-8=>d=1
6.
f:R->R ; f(x)=2x-5
Gf∩Ox=>f(x)=0=>2x-5=0<=>2x=5=>x=5/2=>A(5/2;0)
Gf∩Oy=>x=0=>f(0)=2*0-5=-5=>B(0;-5)
A,B∈Gf
reprezinti punctele in plan si pe acolo trece graficul
8.
f:R->R; f(x)=2x+3
S=f(1)+f(2)+f(3)+...+f(100)
f(1)=2*1+3=2+3=5
f(2)=2*2+3=4+3=7
f(3)=2*3+3=9
f(4)=2*4+3=8+3=11
................................
f(100)=2*100+3=200+3=203
Obs ca termenii sunt termenii unei progresii aritmetice cu ratia r=f(2)-f(1)=7-5=2 si primul termen , a₁=f(1)=5
S₁₀₀=(a₁+an)*n/2=(f(1)+f(100))*100/2=(5+203)*50=208*50=10400
S=10400
