CBSE BoardEnglish MediumSTD 10MathsQuadratic Equations1 Mark
MCQ
$(x + 2)^3= 2x (x^2- 1)$ is a :
A
Bi $-$ quadratic equation
B
Quadratic equation
C
Linear equation
✓
Cubic equation
✓
Answer
Correct option: D.
Cubic equation
Given : $(x+2)^3=2 x\left(x^2-1\right) $
$ \Rightarrow x^3+8+3 x x \times 2(x+2)=2 x^3-2 x $
$ \Rightarrow x^3+8+6 x^2+12 x=2 x^3-2 x $
$ \Rightarrow 2 x^3-x^3-6 x^2-12 x-2 x-8=0 $
$ \Rightarrow x^3-6 x^2-14 x-8=0 $
Here since the degree is $3,$
$\therefore$ it is a cubic equation.
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