Question

Doar ex incercuite .. iar la primul unde e incercuit cu galben fara ala

Answer 1

(x+√5)²-2√5(x+√5)-(x-√5)(x+√5)=
=x²+2x√5+5-2x√5-10-x²+5=0

x(2x+3)-3(x-2)²-(3-x)(x+3)-15x=
=2x²+3x-3x²+12x-12-9+x²-15x=
= - 21

2.in Δ ADE   DE=√(10²-8²)=√(100-64)=√36=6
in ΔADC teorema inaltimii   DE²=AExEC       6²=8xEC     EC=36:8=4,5 cm
AC=AB=8+4,5=12,5 cm
DC=√(12,5²-10²)=√(156,25-100)=√56,25=7.5 cm
BC=2x7,5=15 cm
P=12,5x2+15=40 cm

3. 2 m=20 dm
BE_I_DC  AB=DE=15 dm    EC=20-15=5
AD=BE=√15x5=√75=5√3 dm
BC=√(5√3)²+5²=√(75+25)=√100=10 dm
P=15+20+5√3+10=45+5√3=53,66 dm

4. teorema catetei    c₁=c₂=√7x14=√98=7√2

5. BC=x
DC=x/3
AC=√x×x/3=x/√3=(x√3)/3
BC²=AB²+AC²
x²=8²+[(x√3)/3]²
x²=64+x²/3
3x²=192+x²
2x²=192
x²=96
x=4√6 dm
AC=4√6×√3/3=4√18/3=4√2 dm

1a
BC=20 BD=4   DC=20-4=16
AB=√4+20=√80=4√5
AC=√16+20=√320=8√5

1c
BD=6 DC=8   BC=6+8=14
AB=√6x14=√84=2√21
AC=√14+8=√112=4√7