(5x-3)/5+(3x-1)/4 06/11/2021 Bởi Sadie (5x-3)/5+(3x-1)/4 { "@context": "https://schema.org", "@type": "QAPage", "mainEntity": { "@type": "Question", "name": " (5x-3)/5+(3x-1)/4
Đáp án: \(x > 1,639879256\) Giải thích các bước giải: \(\begin{array}{l}\frac{{5x – 3}}{5} + \frac{{3x – 1}}{4} < \frac{{x\left( {2{x^2} + 3} \right)}}{2} – 5\\ \to \frac{{4\left( {5x – 3} \right) + 5\left( {3x – 1} \right)}}{{20}} – \frac{{10\left( {2{x^3} + 3x} \right) – 5.20}}{{20}} < 0\\ \to 20x – 12 + 15x – 5 – 20{x^3} – 30x + 100 < 0\\ \to – 20{x^3} + 5x + 80 < 0\\Xét: – 20{x^3} + 5x + 80 = 0\\ \to x = 1,639879256\end{array}\) BXD: x -∞ 1,6398 +∞ f(x) + 0 – \(KL:x > 1,639879256\) Bình luận
Đáp án:
\(x > 1,639879256\)
Giải thích các bước giải:
\(\begin{array}{l}
\frac{{5x – 3}}{5} + \frac{{3x – 1}}{4} < \frac{{x\left( {2{x^2} + 3} \right)}}{2} – 5\\
\to \frac{{4\left( {5x – 3} \right) + 5\left( {3x – 1} \right)}}{{20}} – \frac{{10\left( {2{x^3} + 3x} \right) – 5.20}}{{20}} < 0\\
\to 20x – 12 + 15x – 5 – 20{x^3} – 30x + 100 < 0\\
\to – 20{x^3} + 5x + 80 < 0\\
Xét: – 20{x^3} + 5x + 80 = 0\\
\to x = 1,639879256
\end{array}\)
BXD:
x -∞ 1,6398 +∞
f(x) + 0 –
\(KL:x > 1,639879256\)