Question

Помогите пожалуйста ❤️срочноооо

Answer 1

Ответ:

Объяснение:

1.

$(7x-3)*(2+3x)+4*(3x+4)=3x\\21x^2+5x-6+12x+16-3x=0\\21x^2+14x+10=0\ \ \ \ \Rightarrow\\a=21\ \ b=14\ \ c=10.$

2.

$a)\ x^2+x-210=0.$

$b)\ x_1=-4\ \ \ \ x_2=-13.\\\left \{ {{b=-(x_1+x_2)=-(-4+(-13))=-(-17)|=17} \atop {c=x_1*x_2=(-4)*(-13)=52.}} \right.\ \ \ \ \Rightarrow\\x^2+17x+52=0.$

3.

$-2x^2+8x+c=0\\a)\ D=8^2-4*(-2)*c=0\\64+8c=0\\8c=-64\ |:8\\c=-8.\ \ \ \ \Rightarrow\\b)\ -2x^2+8x-8=0\ |:(-2)\\x^2-4x+4=0\\x^2-2*x*2+2^2=0\\(x-2)^2=0\\x-2=0\\x=2.$

4.

$x^2-7x+10=0\\a)\ \left \{ {{-(x_1+x_2)=-7\ |*(-1)} \atop {x_1*x_2=10}} \right. \ \ \ \ \left \{ {{x_1+x_2=7} \atop {x_1*x-2=10}} \right. .\\b)\ \frac{1}{x_1} +\frac{1}{x_2} =\frac{x_1+x_2}{x_1*x_2}=\frac{7}{10} =0,7.$

5.

$x^2-10x+16=0\\a)\ x^2-2*x*5+16+5^2-5^2=0\\x^2-2*x*5+25+16-25=0\\(x-5)^2-9=0.\\b)\ x^2-8x-2x+16=0\\x*(x-8)-2*(x-8)=0\\(x-8)*(x-2)=0.$