Question

solve the following question with step by step explanation no spam​

Answer 1

i)if x=3 then 4×3^3-3×3^2+5×3-6

27×4-27+15-6

108-34+15

123-33

90

ii)if x=-1 then answer is -28

-1^3 -8×-1^2+14×-1 - 7

-30

Answer 2

1. Find the value of 4x³-3x²+5x-6,when x =3.

$x = 3 \: \: \: \: (given)$

$4x {}^{3} - 3x {}^{2} + 5x - 6$

$\star \: \red {putting \: the \: value \: of \: x}$

$4(3) {}^{3} - 3(3) {}^{2} + 5(3) - 6$

$4 \times 27 - 3 \times 9 + 15 - 6$

$\implies \: 108 - 27 + 15 - 6$

$\implies \: 81 + 9$

$\implies \: 90$

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2. Find the value of x³-8x²+14x-7,When x=-1

$x = - 1 \: \: \: (given)$

$x {}^{3} - 8x {}^{2} + 14x - 7$

$( - 1) {}^{3} - 8( - 1) {}^{2} + 14( - 1) - 7$

$\implies \: ( - 1) - 8 \times 1 + ( - 14) - 7$

$\implies \: - 1 - 8 - 14 - 7$

$\implies \: - 9 - 21$

$\implies \: - 30$