х²+12=7х 7у²+5у=2 1+8х=9х²

Question

х²+12=7х 7у²+5у=2 1+8х=9х²

Answer 1

1. х²+12=7х
х²-7x+12=0
D=25
x=6
x=1

2. 7у²+5у=2
7y²+5y-2=0
D=81
x=-1
x=2/7

3. 1+8х=9х²
9х²-8x-1=0
D=100
x=1
x=-1/9