Question

Answer 1

a: Đặt x/3=y/4=k

=>x=3k; y=4k

x^2+y^2=25

=>25k^2=25

=>k^2=1

TH1: k=1

=>x=3; y=4

TH2: k=-1

=>x=-3; y=-4

b: x/5=y/3=k

=>x=5k; y=3k

x^2-y^2=1600

=>25k^2-9k^2=1600

=>k^2=100

TH1: k=10

=>x=50; y=30

TH2: k=-10

=>x=-50; y=-30

c: Đăt x/3=y/7=k

=>x=3k; y=7k

x^2+y^2=58

=>9k^2+49k^2=58

=>k^2=1

TH1: k=1

=>x=3; y=7

TH2: k=-1

=>x=-3; y=-7

d: Đặt x/3=y/4=k

=>x=3k; y=4k

x^2+y^2=400

=>9k^2+16k^2=400

=>k^2=16

TH1: k=4

=>x=12; y=16

TH2: k=-4

=>x=-12; y=-16