The problem is to analyze the inequality $4x^2 + 8xy + 3y^2 > 0$. We want to determine the conditions on $x$ and $y$ that make this inequality true.

AlgebraInequalitiesQuadratic ExpressionsFactoringLinear Inequalities2D Geometry
2025/7/7

1. Problem Description

The problem is to analyze the inequality 4x2+8xy+3y2>04x^2 + 8xy + 3y^2 > 0. We want to determine the conditions on xx and yy that make this inequality true.

2. Solution Steps

We can factor the quadratic expression:
4x2+8xy+3y2=(2x+y)(2x+3y)4x^2 + 8xy + 3y^2 = (2x + y)(2x + 3y)
So, we have the inequality (2x+y)(2x+3y)>0(2x + y)(2x + 3y) > 0.
This inequality holds if both factors are positive or both factors are negative.
Case 1: Both factors are positive.
2x+y>02x + y > 0 and 2x+3y>02x + 3y > 0
y>2xy > -2x and 3y>2x3y > -2x, so y>23xy > -\frac{2}{3}x
In this case, since 2<23-2 < -\frac{2}{3} is false, we need both inequalities to hold, so y>23xy > -\frac{2}{3}x.
Case 2: Both factors are negative.
2x+y<02x + y < 0 and 2x+3y<02x + 3y < 0
y<2xy < -2x and 3y<2x3y < -2x, so y<23xy < -\frac{2}{3}x
In this case, since 2<23-2 < -\frac{2}{3}, we need both inequalities to hold, so y<2xy < -2x.
However, if y=0y=0, the inequality becomes 4x2>04x^2 > 0, which is true for x0x \ne 0. Thus, xx can be non-zero when y=0y=0.
Combining these cases, we have y>23xy > -\frac{2}{3}x or y<2xy < -2x.
Notice that if x=0x = 0, then 3y2>03y^2 > 0 implies y0y \neq 0.
If y=0y = 0, then 4x2>04x^2 > 0 implies x0x \neq 0.
Also, if y=xy = -x, we have 4x28x2+3x2=x2>04x^2 - 8x^2 + 3x^2 = -x^2 > 0, which is never true.
If y=2xy = -2x, we have 4x216x2+12x2=04x^2 - 16x^2 + 12x^2 = 0, which is not greater than

0. If $y = -\frac{2}{3}x$, we have $4x^2 - \frac{16}{3}x^2 + \frac{4}{3}x^2 = \frac{12 - 16 + 4}{3}x^2 = 0$, which is not greater than

0. Therefore the inequality holds if $y > -\frac{2}{3}x$ or $y < -2x$. We must also exclude the lines $y = -\frac{2}{3}x$ and $y=-2x$. Also exclude the point $(0,0)$.

3. Final Answer

The inequality 4x2+8xy+3y2>04x^2 + 8xy + 3y^2 > 0 holds if y>23xy > -\frac{2}{3}x or y<2xy < -2x. We must exclude the lines y=23xy = -\frac{2}{3}x and y=2xy=-2x. Also, we must exclude the point (0,0).