book Maths Puzzle Numerical Ability

check my work please:
4x^2+8x=0
4x(x+2)=0
4x=0 or (x+2)=0
4x=0 or x=-2

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book Other Question

solve each quadratic equation written in vertex form.
2(x+3)^2-4=0
3/4 n=16

2/5 n=30

-7/15 =21/10

n.5/16=15/14