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3 years ago

What is (4x+3)(x-7)=90

2 answers:

8 0

$(4x+3)(x-7)=90\\
Distribute\\
4x^{2}-28x+3x-21=90\\
4x^{2}-25x-21=90\\
4x^{2}-25x-101=0\\
\\
101\ is\ a\ prime\ number,\ so\ use\ the\ quadratic\ equation.\\
x= \frac{-b+-\sqrt{b^{2}-4ac}}{2a} \\
 \frac{-(-25)+-\sqrt{(-25)^{2}-4*4*(-101)}}{2*4} \\
 \frac{25+-\sqrt{625+1616}}{8} \\
x= \frac{25+-\sqrt{2241}}{8} \\
So\ x= \frac{25+\sqrt{2241}}{8}\ and x= \frac{25-\sqrt{2241}}{8} \\
These\ come\ out\ to\ be\ x=9.0424... \ and\ x=-2.7924...$

Ivan3 years ago

6 0

It would be 16 i say

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aleksklad [387]

Hope this helps you :), this qn is tedious so i might make careless mistakes. Best to check with your licensed tutor or your school teacher :)

4 0

3 years ago

1. The standard form of a quadratic equation is

amm1812

Answer:

$ax^2+bx+c=0$

Step-by-step explanation:

The standard form of quadratic equation is $ax^2+bx+c=0$ where a,b and c are real numbers and a ≠ 0.

6 0

3 years ago

Solve the equations 1. 16x^2-1=0 2. 36z^2 96z 15=0

Allisa [31]

$16x^2-1=0 2$

$16x^2-1=0 2:x$

$
16x^2=1
 
$ $|Add \ 1 \ to \ both \ sides|$

$x^2= \dfrac{1}{16}$ $|Divide \ both \ sides \ by \ 16|$ <span>
</span>
$x^2= \sqrt{\dfrac{ \sqrt{1}}{ \sqrt{16}}}$ $|Take \ the \ square \ root \ of \ both \ sides|$

$x= \dfrac{1}{4}$

5 0

3 years ago

Help plzzzzz hurry

V125BC [204]

Answer:

-9, -5, -4.1, -4

$\\q\leq -4$

Step-by-step explanation:

I think what you're missing here is that there is a negative sign in front of the q. This means that whatever number you put in for q will be multiplied by negative 1. Positive numbers will become negative, and negative numbers will become positive.

If you substitute 9 for q you will get $-9\geq 4$ , which is clearly not true, because -9 is way less than 4.

For writing the equation you divide both sides by -1. When you do this however, you must flip the inequality sign

$-q\geq 4\\q\leq -4$

the > sign turned into <, and the q and 4 switched signs.

6 0

3 years ago

Please show work on how you got the answer

Maurinko [17]

Since E is the midpoint, DE and EF are the same length.
Set the equation DE and EF equal to each other and solve for x.
2x + 4 = 3x - 1
x = 5
Then plug in 5 to find the length.
DE = 2(5) + 4 = 14
EF = 3(5) - 1 = 14
DF = DE + EF = 28

3 0

4 years ago