Find the

Find the number x, which if it increases by 2, then its square increases by 21 percent.

Correct answer:

x =  20
y =  -0.9524

Step-by-step explanation:

q=100%+21%=1+10021=1.21  (x+2)2=x2 q  (x+2)2=x2 1.21 0.21x2+4x+4=0 0.21x24x4=0  a=0.21;b=4;c=4 D=b24ac=4240.21(4)=19.36 D>0  x1,2=2ab±D=0.424±19.36 x1,2=9.52381±10.47619 x1=20 x2=0.952380952  x=x1=20

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