Question

Can you answer question 9, 10, and 11 for me with showing your steps

Answer 1

Answer:

9th question :

(a)

I) area = x(x+5) = x² + 5x  II) perimeter = 2(2x + 5) = 4x + 10

(b) 4x + 10 = 21.6

⇒4x = 11.6

⇒x = 2.9

Area = (2.9)² + 5(2.9)

        = 8.41 + 14.5

        = 22.91

(c) x² + 5x = 176

⇒x² + 5x - 176 = 0

⇒x² + 16x - 11x - 176 = 0

⇒x( x + 16) - 11( x + 16) = 0

⇒(x - 11)(x + 16) = 0

∴ x = 11

10th question :

h = b - 4

area = 1/2 × b × h  =  1/2 × b(b-4)

⇒1/2 × b² - 4b = 77 × 1/2

⇒b² - 4b = 77

⇒b² - 4b - 77 = 0

⇒b² - 11b + 7b - 77 = 0

⇒b(b - 11) + 7(b -11) = 0

⇒(b - 11)(b + 7) = 0

⇒b = 11

∴ Base = 11 cm

11th question :

Let the two sides of the rectangle be a & b.

b = a - 3

Area = a(a - 3)

⇒ a² - 3a = 154

⇒ a² - 3a - 154 = 0

⇒ a² - 14a + 11a - 154 = 0

⇒ a( a - 14) + 11(a - 14) = 0

⇒ (a - 14)(a + 11) = 0

∴ a = 14 cm

Perimeter = 2(a + b) = 2(14 + 14 - 3) = 2(25) = 50 cm²