a) a²=(√4-√15)²+2(4-√15)(4+√15)+(√4+√15)²=4-√15+2(16-15)+4+√15=8+2=10
c) 3x^4+9x²-5x³-25=3x^4-5x³+9x²-15x+15x-25=3x^4+9x²+15 -5x³-15x-25=
3x(x³+3x+5)-5(x³+3x+5)=(x³+3x+5)(3x-5)
b)a=√(a^4+3^5)
ca sa scapi de radical ridici la patrat si in stanga si in dreapta egalului
a²=a^4+243
a^4-a²+243=0
notam a²=y
y²-y+243=0
daca calcula solutiile vor fi valori in numere complexe ceea ce voi nu ati invatat.
daca o luam babeste
3²√3=√243
√243=√(a²+3^5)
243=a²+243
deci a=0 si nu e in regula