Question

please am avut-o in test +coroana

Answer 1

sub 1
1. 18-12:3=18-4=14
2.-8 mai mic decat minus 3
3. x-3=-1
   x=-1+3
   x=2
4.  fiecare unghi al unui triunghi echilateral are masura egala cu 60 grade
5. suma masurilor unui triunghi este egala cu 160 grade
6. numar elevi clasa a VII=VII A+VII B= 32+29=61 elevi

sub 2
1. ti-am facut pe foaie
2. -6+12:(-2)+(-2)³= -6+(-2)+(-8)=-6-6-8=-12-8=-20
3 maria avea x suma de bani
x-20% din x=80
x-20/100×x=80 (dae 20/100 se simplifica cu 10=2/10 care se simplifica cu 2=1/5)
x-1/5×x=80
x-x/5=80 (aduc la acelasi numitor)
5x/5-x/5=80×5/5
4x/5=400/5<=> 4x=400=>x=400:4=>x=100

4. 2x=5y
a)x/y=?
2x=5y=> x=5y/2
x/y=5y/2/y=5y/2:y=5y/2×1/y=5y/2y care se simplifica cu y=5/2

b)(2x-y)/(x+y)=?
2x-y=5y-y=4y
x+y=5y/2+y (aduc la acelasi numitor)= 5y/2+2y/2=7y/2
deci (2x-y)/(x+y)=4y/7y/2=4y:7y/2=4y×2/7y=8y/7y (se simplifica cu y)=8/7

5.
x/7=y/8=z/10=k
x+y+z=250

x/7=k=>x=7k
y/8=k=>y=8k
z/10=k=>z=10k
7k+8k+10k=250
25k=250=>k=250:25=> k=10
x=7k=>x=7×10=>x=70
y=8k=>y=8×10=>y=80
z=10k=>z=10×10=>z=100

sub 3.
1. desenul e pe foaie...e cel cu rosu
Δadc:
m(∡acd)=180-m(∡cad)-m(∡adc)=180-30-90=60 grade
Δabc
m(∡abc)=180-m(bac)-m(∡acb)=180-90-60=30 grade
aplicam teorema unghiului de 30 grade=> ac=bc/2=> ac=12/2=> ac=6
in Δacd: m(∡cad)=30 grade
aplic teorema unghiului de 30 grade=> cd=ac/2=> cd=6/2=> cd=3

2. figura e pe foaie..are culoarea albastra
in Δdbc:
m(∡dcb)=180-(m∡bdc)-m(∡dbc)=180-90-20=70 grade
daca Δabc isoscel=> m(∡acb)≡m(∡abc) 
                          daca m(∡acb)=70 grade=> m(∡abc)=70 grade

m(bac)=180-70-70=40 grade

deci unghi a=40 grade, unghi b=70 grade si unghi c=70 grade