Simplify $3 x (4 - 5 x) + 6$ and find its values for $x = 3$

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Solution

given, $3 x (4 - 5 x) + 6$

$= 12 x - 15 x^{2} + 6$

$= - 3 (5 x^{2} - 4 x - 2)$ at $x = 3$

$= - 3 (5 \times 3^{2} - 4 \times 3 - 2)$

$= - 3 (45 - 12 - 2)$

$= - 93$

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Similar questions

3 x (4 x - 5) + 3

x = 3

A = \frac{{3 x}^{4}}{4} - \frac{x^{4}}{2} + 5 x - 7; B = \frac{{2 x}^{3}}{3} + \frac{{3 x}^{3}}{2} - \frac{x}{6}; C = \frac{{2 x}^{4}}{3} - \frac{{3 x}^{4}}{4} + 5

B A

A = \frac{{3 x}^{4}}{4} - \frac{x^{4}}{2} + 5 x - 7; B = \frac{{2 x}^{3}}{3} + \frac{{3 x}^{3}}{2} - \frac{x}{6}; C = \frac{{2 x}^{4}}{3} - \frac{{3 x}^{4}}{4} + 5

(- A) C

A = \frac{{3 x}^{4}}{4} - \frac{x^{4}}{2} + 5 x - 7; b = \frac{{2 x}^{3}}{3} + \frac{{3 x}^{3}}{2} - \frac{x}{6}; C = \frac{{2 x}^{4}}{3} - \frac{{3 x}^{4}}{4} + 5

- A + B - C

5 x^{2} - 4 - 3 x^{2} + 6 x + 8 + 5 x + 3

x = - 2

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