+0  
 
0
92
2
avatar

Write down the quadratic equation whose roots are x = -7 and x = 8 and the coefficient of x^2 is 1.

Enter your answer in the form "x^2 + bx + c = 0".

 Jul 3, 2021
 #1
avatar
0

\(x^2+x-56=0\)

.
 Jul 3, 2021
edited by Guest  Jul 3, 2021
 #2
avatar+151 
+1

that is just a little off.

 

x^2 + bx + c = 0

 

we know that one solution is -7, and the other one is 8

that means:

 

$\left. \begin{array}
 \ x=-7 \\ x=8 
\end{array} \right\}  \implies \left. \begin{array}
 \ x+7=0 \\  x-8=0 
\end{array} \right\} $    knowing that we can write the quadratic as a factorised form$ (x+7)(x-8)  $

 

 

new lets find the quadratic:

 

$  (x+7)(x-8) \overset{\left(m+n\right)\left(p-q\right) = mp-mq+np-nq }{=============\Rightarrow} xx+x\left(-8\right)+7x+7\left(-8\right) $

 

$xx-8x+7x-7\cdot \:8$

 

$ \boxed{ x^2-x-56 } $

 Jul 3, 2021

42 Online Users

avatar