Question

-Q.5
Which of the following quadratic equations have x=3 as one of its roots.
(A) x - 8x +15=0
(B) x +8x +15=0
(C) X-8x – 15=0
(D) x'+8x –15=0​

Answer 1

Question

Which of the following quadratic equations have x=3 as one of its roots.

(A) x - 8x +15=0

(B) x +8x +15=0

(C) X-8x – 15=0

(D) x'+8x –15=0

Answer

Given↓

(A) x - 8x +15=0

(B) x +8x +15=0

(C) X-8x – 15=0

(D) x'+8x –15=0

(A) x - 8x +15=0

If x = 3

→x - 8x +15=0

→x - 8x +15=0

→7×3= 15

→21 = 15

→21 - 15 ≠ 0

(B) x +8x +15=0

If x = 3

→9x = -15

→9×3 = -15

→27 = -15

→27 + 15 ≠ 0

(C) x-8x – 15=0

If x = 3

→-7x = 15

→-7×3 = 15

→-21 = 15

-21-15 ≠ 0

(D) x+8x –15=0

If x = 3

→9x = 15

→9×3. = 15

→27 = 15

→27-15 ≠0

As proved above, none of the quadratic equations have x=3 as its roots