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

1) х²-7х+12=0по теореме Виетах₁+х₂ = 7х₁*х₂ = 12х₁ = 3х₂ = 42) х²-х+9 = х²+4х+44х+х = 9-45х = 5х = 13) 7у²+5у-2=0Д = 5²-4*7*(-2) = 25+56 = 81 = 9²у₁ = (-5+9)/14 = 2/7у₂ = (-5-9)/14 = -14) х²+20х+100 = 144 -24х+х²24х+20х = 144-10044х = 44х =15) 9х² -8х - 1 = 0Д = 64 - 4*9*(-1) = 64+36 = 100 = 10²х₁ = (8-10)/18 = -2/18 = -1/9х₂ = (8+10)/18 = 1