Question

x2 +10x+21=0

Answer 1

x2+7x+3x+21
(x+7)(x+3)

Answer 2

help

Answer 3

To solve a quadratic equation by factoring, you first factor the left side by figuring out what multiplies to make 21 and adds to make 10. Since the answer is 7 and 3, the equation is now (x+7)(x+3)=0. Then (by the Zero Factor Theorem), if the two factors are multiplying to make 0, one of them has to equal zero. So you write
x+7=0 or x+3=0
and solve each equation so you get x=-7 and x=-3.

Answer 4

dear he need only idea ok

Answer 5

(x+7)(x+3)
x=-7or-3