if x is equal to 1 / 2 - root 3 find the value of x cube - x square - 11x + 5
(A) 1
(B) 2
(C) 3
(D) 4
Answers
Answered by
1
Answer:
x=
2−
3
1
Multiplying the numerator and denominator by the conjugate of the denominator, we have
x=
2−
3
1
×
2+
3
2+
3
=
2
2
−
3
2
2+
3
=
4−3
2+
3
=2+
3
⇒x
2
=(2+
3
)
2
=4+4
3
+3=7+4
3
Now consider the given expression
x
3
−2x
2
−7x+5=x
3
−7x−2x
2
+5
⇒=x(x
2
−7)−2x
2
+5
⇒=(2+
3
)(7+4
3
−7)−2(7+4
3
)+5
⇒=(2+
3
)(4
3
)−14−8
3
+5
⇒=8
3
+12−14−8
3
+5
⇒=3
x
3
−2x
2
−7x+5=m{Given}
∴m=3
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