Roots and coefficient

In the equation 2x2 + bx-9 = 0 is one root x1 = -3/2. Determine the second root and the coefficient b.

Correct answer:

b =  -3
x2 =  3

Step-by-step explanation:

a=3/2=23=121=1.5  2 a2+b a9=0 2 (1.5)2+b (1.5)9=0  1.5b=4.5  b=1.54.5=3  b=3
2 x2+b x9=0  2 x2+(3) x9=0 2x23x9=0  a=2;b=3;c=9 D=b24ac=3242(9)=81 D>0  x1,2=2ab±D=43±81 x1,2=43±9 x1,2=0.75±2.25 x1=3 x2=1.5  x2=x1=3

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