What number must be added to the expression below to complete the square? x^2-9x

Mathematics

2 answers:

Tatiana [17]3 years ago

5 0

Answer:

A.81/4

Step-by-step explanation:

To find the number that we add to complete the square, we take half of the value of b in the equation and then square it.

The value of b in this equation is -9; this makes half of it -9/2. Squaring this,

(-9/2)² = 81/4.

pantera1 [17]3 years ago

3 0

Answer:

A.81/4

Step-by-step explanation:

x^2-9x

This is in the form x^2 + bx

To complete the square, we take b/2 then square it and add it

b =-9

b/2 = -9/2

(b/2) ^2 = (-9/2) ^2 = 81/4

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7x-2y=16 11x+6y=32.3<br>how to solve this math problem

Aneli [31]

Answer:

Step-by-step explanation:

These types of equations are called simultaneous equations and the method we can use to solve these type of equations is either Substitution, Elimination and Graphing.

We use substitution here because it is easier.

Equation 1

$7x-2y=16$

Equation 2

$11x+6y=32.3$

Lets take equation 1

$7x-2y=16\\7x=16+2y\\x=\frac{16+2y}{7}$

This is our equation 3 , now put it inside equation 2.

$11x+6y=32.3\\11(\frac{16+2y}{7} )+6y=32.3\\\frac{176+22y}{7} +6y=32.3\\\frac{176+22y+42y}{7}=32.3\\176+22y+42y=226.1 \\\\42y+22y=226.1-176\\64y=50.1\\y=\frac{50.1}{64} \\y=0.783\\$

We found the value of y , now to find the value of x insert the value of y in equation 3

$x=\frac{16+2y}{7}\\x=\frac{16+2(0.783)}{7} \\x=\frac{16+1.566}{7}\\x=\frac{17.566}{7}\\x=2.509$

Solved ! See the attached image on both the straight line graphs i have attached for better understanding. Where both the lines intersect each other is our value of (x , y) respectively.