Update Unit 2: Quadratic Equations 1.md

Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Unit 2: Quadratic Equations 1.md

@@ -25,15 +25,19 @@ Let $`h`$ be the height and $`b`$ be the base. $`h = 2b + 4`$.
 
 $`\therefore (2b+4)(b) = 168(2)`$
 
-$`2b^2 + 8b = 168(2)`$
+$`2b^2 + 4b = 168(2)`$
 
-$`b^2 + 4b - 168 = 0`$
+$`b^2 + 2b - 168 = 0`$
 
-$`b = \dfrac{-4 \pm \sqrt{16+4(168)}}{2}`$
+$`b = \dfrac{-2 \pm \sqrt{4+4(168)}}{2}`$
 
-$`b = \dfrac{-4 \pm 4\sqrt{43}}{2}`$
+$`b = \dfrac{-2 \pm 26}{2}`$
 
-$`b = -2 + 2\sqrt{85}`$
+$`b = -1 \pm 26 \implies b = 25, -27`$
+
+$`\because b \gt 0 `$
+
+$`\therefore b = 25cm`$
 
 ### Question 2 a)