5. Answer: see explanation
Step-by-step explanation:
If the roots are m and 3m, then x = m and x = 3m
⇒ x - m = 0 and x - 3m = 0
⇒ (x - m)(x - 3m) = 0
⇒ x² - 4mx + 3m² = 0
Since x² + px + q = 0 then p = -4m and q = 3m²
3p² = 3(-4m)² 16q = 16(3m²)
= 3(16m²) = 48m²
= 48m²
3p² = 48m² = 16q ⇒ 3p² = 16q
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6. Answer: 8 or 18
Step-by-step explanation:
The Area of the entire rectangle (A = L × w) is 12 × 10 = 120
The Area of the shaded region is 72, so the Area of the non-shaded region is 120 - 72 = 48.
There are two non-shaded triangles.
- Bigger non-shaded Δ: L = 12-x, w = 10 ⇒ [tex]A = \dfrac{10(12-x)}{2}[/tex]
- Smaller non-shaded Δ: L = x, w = x ⇒ [tex]A=\dfrac{x(x)}{2}[/tex]
Combine the Areas of both triangles and set it equal to the Area of the non-shaded region:
[tex]\dfrac{x(x)}{2}+\dfrac{10(12-x)}{2}=48\\\\\\\dfrac{x^2}{2}+\dfrac{120-10x}{2}=48\\\\\\\dfrac{x^2-10x+120}{2}=48\\\\\\x^2-10x+120=96\\\\x^2-10x+24=0\\\\(x-4)(x-6)=0\\\\x - 4 = 0\quad or\quad x-6=0\\x=4\qquad or\qquad x=6\\\\\text{Based on the image provided, it appears that the x-value will be the}\\\text{smallest of the two possible solutions (4), but both solutions are valid.}[/tex]
Area of ΔBEF:
[tex]\text{when x = 4, A =}\ \dfrac{4(4)}{2}=\dfrac{16}{2}=8\\\\\\\text{when x = 6, A =}\ \dfrac{6(6)}{2}=\dfrac{36}{2}=18[/tex]
