Question

Which of the following is a quadratic equation ?

(x+b)(x-1)=x²-4x+9

(x-3)(2x+1)=x(x+5)

x²+3x+1=(x-2)²

(x+1)²-x(x-3)=0

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Answer 1

Step-by-step explanation:

1) x(x-1)+x(x-1)=x²-4x+9

x²-x+x²-x=x²-4x+9

2x²=x²-4x+9

2x²-x²=-4x+9

x²=-4x+9

x²+4x-9=0

therefore it is a quadratic equation because it has x².

now do the same with other if there is x² then yes and if more than x² like x³ then no.

...hope it helps u...

r u in 10th std