help!

If x be the real number such that x3+4x = 8 then the value of the expression x7 + 64x2 is
1. 124
2. 125
3. 128
4. 132

1 Answers

62
Lokesh Verma ·

Hint:
x3=8-4x

x7=8x4-4x5

Hence the given expression is -4x5+8x4+64x2

Now try to simplify further.....

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