Question

2. find the x -intercept about \( y=x^{2}+3 x-4 \)

Ask by Coles Dickson. in the United Arab Emirates
Jan 24,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

函数 \( y = x^{2} + 3x - 4 \) 的 x 截距是 \( x = 1 \) 和 \( x = -4 \)。

Solution

要找到函数 \( y = x^{2} + 3x - 4 \) 的 x 截距,需令 \( y = 0 \) 并解方程: \[ x^{2} + 3x - 4 = 0 \] 使用求根公式: \[ x = \frac{-b \pm \sqrt{b^{2} - 4ac}}{2a} \] 其中,\( a = 1 \),\( b = 3 \),\( c = -4 \)。 首先计算判别式: \[ \Delta = b^{2} - 4ac = 3^{2} - 4 \times 1 \times (-4) = 9 + 16 = 25 \] 然后代入公式求解: \[ x = \frac{-3 \pm \sqrt{25}}{2} = \frac{-3 \pm 5}{2} \] 得到两个解: \[ x = \frac{-3 + 5}{2} = 1 \] \[ x = \frac{-3 - 5}{2} = -4 \] 因此,函数 \( y = x^{2} + 3x - 4 \) 的 x 截距为: \[ x = 1 \quad \text{和} \quad x = -4 \]

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To find the x-intercept of the equation \( y = x^2 + 3x - 4 \), set \( y = 0 \). This gives us the equation \( x^2 + 3x - 4 = 0 \). Using the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \) with \( a = 1, b = 3, c = -4 \), we find the square root discriminant to be \( b^2 - 4ac = 3^2 - 4(1)(-4) = 9 + 16 = 25 \). Plugging this into the formula yields the x-intercepts as \( x = \frac{-3 \pm 5}{2} \), giving us \( x = 1 \) and \( x = -4 \). Picture this: We're not just finding a couple of points on a graph; we’re uncovering where our quadratic curve meets the x-axis! These intercepts (1 and -4) tell you exactly where the function goes from positive to negative or vice versa. It's like the magic crossover moment of a thrilling sports match, where the ball lands just inside the line!

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