Question

ache o valor do Delta e do X

2x2 – 9x + 4 = 0

Answer 1

2x² - 9x + 4 = 0

a = 2

b = - 9

c = 4

∆ = b² - 4 . a . c

∆ = (-9)² - 4 . 2 . 4

∆ = 81 - 32

∆ = 49

x = - b ± √∆

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2a

x' = - (-9) - 7

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2 . 2

x' = 9 - 7

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4

x' = 2 (÷2)

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4 (÷2)

x' = 1

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2

x" = - (-9) + 7

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2 . 2

x" = 9 + 7

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4

x" = 16

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4

x" = 4

S = {(1/2 , 4)}

Answer 2

$\large\boxed{\begin{array}{l} \rm \: 2x {}^{2} - 9x + 4 = 0 \\ \\ \hookrightarrow \begin{cases} \rm \: a = 2 \\ \rm \: b = - 9 \\ \rm \: c = 4\end{cases} \\ \\ \rm\Delta = b {}^{2} - 4ac \\ \Delta = ( - 9) {}^{2} - 4 \: . \: 2 \: . \: 4 \\ \Delta = 81 - 32 \\ \Delta = 49 \\ \\ \rm \: x = \dfrac{ - b \pm \sqrt{\Delta} }{2a} \\ \\ \rm \: x = \dfrac{ - ( - 9) \pm \sqrt{49} }{2.2} \\ \\ \rm \: x = \dfrac{9 \pm7}{4}\begin{cases} \rm \: x_1 = \dfrac{9 + 7}{4} = \dfrac{16}{4} = \boxed{4} \\ \\ \rm \: x_2 = \dfrac{9 - 7}{4} = \dfrac{2}{4} = \boxed{ \frac{1}{2} } \end{cases} \end{array}}$