Solve the following equation by transforming it into a perfect square trinomial.

3x2 + 12x = 63

A.
{–27, 23}

B.
{–29, 21}

C.
{–7, 3}

D.
{–9, 1}

Question

Solve the following equation by transforming it into a perfect square trinomial.
 
        3x2 + 12x = 63
 
 
 A.
{–27, 23}
 
 B.
{–29, 21}
 
 C.
{–7, 3}
 
 D.
{–9, 1}

anonymous · Answer

Factor the equation above:
$$3(x ^{2}+4x-21)=0$$
3(x+7)(x-3)=0
solve for x

anonymous · Answer

x=-7 and x=3   C

anonymous · Answer

Thank you for explaination but I didnt get it. Thank you though! :)

hartnn · Answer

you know how to make a trinomial, a perfect square ?
what steps have you tried yet ?

anonymous · Answer

this equation can be factored rather easily
3x^2 + 12x = 63 so in order to factor we need to set the equation equal to zero
3x^2+12x-63=0  all these numbers are divisible by 3 so we factor 3 out
3(x^2+4x-21)=0  so the factors of -21 that have the sum of 4 are 7 & -3 so
3(x+7)(x-3)=0      now we set the factors equal to zero 
x+7=0       x-3=0
x=-7          x=3         C
Does this help a bit?

hartnn · Answer

solved any problem of completing the square ?

anonymous · Answer

yes

hartnn · Answer

so, first. bring it in the form of 
x^2+bc+c=0
could u?

hartnn · Answer

**x^2+bx+c=0