11th grade
posted by bob .
20xsquared+40 x+15=0

factor out 5
u get
5(4x^2+8x +3) = 0
5(4x^2+2x+6x+3)=0
5(2x(2x+1)+3(2x+1))=0
5(2x+1)(2x+3)=0
x=1/2
or
x=3/2
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