Please help I can’t understand how to solve this problem

Mathematics

1 answer:

Pavel [41]3 years ago

8 0

The perimeter of the rectangle:

2(4y)+2(3y+3) and 146 units.

We have the equation:

$2(4y)+2(3y+3)=146\qquad|\text{use distributive property}\\\\8y+(2)(3y)+(2)(3)=146\\\\8y+6y+6=146\qquad|\text{combine like terms}\\\\14y+6=146\qquad|\text{subtract 6 from both sides}\\\\14y=140\qquad|\text{divide both sides by 14}\\\\y=10\\\\AD=4y\to AD=4(10)=40$

Answer: AD = 40 units.

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Solve x2 - 8x - 9 = 0. Rewrite the equation so that it is of the form x2 + bx = c.

barxatty [35]

Answer:

x=9,-1 and $x^2+(-8)x=9$

Explanation:

we have been given with the quadratic equation $x^2-8x-9$

we compare the given quadratic equation with general quadratic equation

general quadratic is $ax^2+bx+c=0$

from given quadratic equation a=1,b= -8,c= -9

substituting these values in the formula for discriminant $D=b^{2}-4ac$

$D=(-8)^2-4(1)(-9)=100$

Now, to find the value of x

Formula is $x=\frac{-b\pm\sqrt{D}}{2a}$

Now, substituting the values we will get

$x=\frac{-(-8)\pm\sqrt{100}} {2}= \frac{8\pm10}{2}=9,-1$

And rewritting the given equation by shifting 9 to right hand side of the given equation and taking minus inside the bracket so as to convert it in the form of

$x^2+bx=c$