Question

1.) x² +12=7x
2.) x² - x+9 = ( x+2 )²
3.) 7y² + 5y = 2
4.) ( x + 10 ) ² = ( 12 - x ) ²
5.) 1+8x=9x²

Answer 1

1) х²-7х+12=0
по теореме Виета
х₁+х₂ = 7
х₁*х₂ = 12
х₁ = 3
х₂ = 4

2) х²-х+9 = х²+4х+4
4х+х = 9-4
5х = 5
х = 1

3) 7у²+5у-2=0
Д = 5²-4*7*(-2) = 25+56 = 81 = 9²
у₁ = (-5+9)/14 = 2/7
у₂ = (-5-9)/14 = -1

4) х²+20х+100 = 144 -24х+х²
24х+20х = 144-100
44х = 44
х =1

5) 9х² -8х - 1 = 0
Д = 64 - 4*9*(-1) = 64+36 = 100 = 10²
х₁ = (8-10)/18 = -2/18 = -1/9
х₂ = (8+10)/18 = 1