Verified answer

х²+2х+1=0

(x+1)²=0

x+1=0

x= -1

____________

4x²-3x+5=0

a=4;b= -3; c=5

D=b²-4ac=9-80<0 нет корней

____________

4х²-8х-3=0

a=4; b= -8; c= -3

D=b²-4ac= 64+48= 112

√112=√(16*7)= 4√7

x1;2=(-b±√D)/(2a)

x1=(8-4√7)/8=(4(2-√7))/8= (2-√7)/2

x2=(8+4√7)/8=(4(2+√7))/8=(2+√7)/2

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x²-8x√2 -40=0

x²-8√2 *x-40=0

D=(-8√2)²-4*1*(-40)=64*2+160=288

√288=√(144*2)=12√2

x1=(8√2-12√2)/2=(-4√2)/2= -2√2

x2=(8√2+12√2)/2=(20√2)/2=10√2

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4+9x²+15x=0

9x²+15x+4=0

D=225-144=81=9²

x1=(-15-9)/18= -24/18= -4/3= -1 ⅓

x2=(-15+9)/18= -6/18 = -1/3