Question

toan vio vong 14 lop 8 bai1 cac ban oi

Answer 1

5

Answer 2

Ta có: \(\left(x+y\right)^2=x^2+2xy+y^2=7\)

\(\Rightarrow2xy+3=7\)

\(\Rightarrow2xy=4\)

\(\Rightarrow xy=2\)

Thay xy = 2 vào xyz = 60 ta có:

\(2z=60\)

\(\Rightarrow z=30\)

Vậy z = 30

Answer 3

30 bạn nhé

Answer 4

ta có: (x+y)²=7 (gt)

=>x²+2xy+y²=7

=>2xy=7-(x²+y²)

=>2xy=7-3

=>2xy=4

=>xy=2

mà xyz=60 (gt)

=>2z=60

=>z=30

Answer 5

(x+y)\(^2\)=x\(^2\)+ 2xy+y\(^2\)=3+2xy=7

suy ra 2xy=4 nên xy=2

xyz=2*z=60

nên z=30