(2x-10)(x+5)=x^2+10x-75
that's what i did:
2x^2-50=x^2+10x-75
2x^2-x^2-10x=50-75
x^2-10x=-25
x(x-10)=-25
so what's the next step?
+26393 (2x-10)(x+5)=x^2+10x-75
okay: x^2-10x=-25
now: $$x^2-10x+25=0$$
use the abc - formula:
if $$ax^2+bx+c = 0$$ than $$x_{1,2} = \frac{1}{2a}*(b-\sqrt{b^2-4*a*c})$$
$$1x^2 -10x+25=0 \\
\underbrace{1}_{a=1}x^2 \underbrace{-10}_{ b=-10}x+\underbrace{25}_{c=25}=0 \\\\
x_{1,2} = \frac{1}{2*1}*(10-\sqrt{100-4*1*25})\\\\
x_{1,2} = \frac{1}{2}*(10-\sqrt{100-100})\\\\
x = \frac{1}{2}*(10-0)\\\\
x = \frac{1}{2}*10\\\\
x = \frac{10}{2}\\\\
x = 5$$
+26393 (2x-10)(x+5)=x^2+10x-75
okay: x^2-10x=-25
now: $$x^2-10x+25=0$$
use the abc - formula:
if $$ax^2+bx+c = 0$$ than $$x_{1,2} = \frac{1}{2a}*(b-\sqrt{b^2-4*a*c})$$
$$1x^2 -10x+25=0 \\
\underbrace{1}_{a=1}x^2 \underbrace{-10}_{ b=-10}x+\underbrace{25}_{c=25}=0 \\\\
x_{1,2} = \frac{1}{2*1}*(10-\sqrt{100-4*1*25})\\\\
x_{1,2} = \frac{1}{2}*(10-\sqrt{100-100})\\\\
x = \frac{1}{2}*(10-0)\\\\
x = \frac{1}{2}*10\\\\
x = \frac{10}{2}\\\\
x = 5$$
