Question

Find the products using suitable identity:

a) (t –2)(t –2)
b) (3y –2z) (3y + 2z)
c) 105 × 98

Answer 1

Hello!

a) (t - 2)(t - 2) = (t - 2)² = t² - 4t + 4

b) (3y - 2z)(3y + 2z) = (3y)² - (2z)² = 9y² - 4z²

c) 105 × 98 = 10290

Good luck! :)

Answer 2

Explanation:

a) Identity : (a- b)² = a²- 2ab + b²

(t - 2)(t -2) = (t-2)² {a = t & b =2}

= t² -2*t*2 + 2²

= t² - 4t + 4

b) (a + b)(a - b) = a² - b²

a = 3y & y = 2z

(3y - 2z) (3y +2z) = (3y)² - (2z)²

= 3²y² - 2²z²

= 9y² - 4z²

c) (x + a)(x + b) =x² + (a+b)x + ab

105 * 98 = (100 + 5) (100 - 2) {here, x = 100 ; a = 5 ; b = -2}

= 100² + (5 +(-2) ) *100 + (5)*(-2)

= 10000 + (3)*100 - 10

= 10000 + 300 - 10

= 10290