5x^2+ 15x – 140 = 0
Solve for x

x = 4, -7

Step-by-step explanation:

1. Solve the equation using the quadratic formula

The Quadratic formula provides the solution for

in which A, B, and C are numbers (or coefficients), as follows:

2. Determine the quadratic equation’s coefficients A, B, and C

The coefficients of our equation, , are:

A = 5

B = 15

C = -140

3. Plug these coefficients into the quadratic formula

Calculate the expression inside the parentheses.

Simplify exponents and square roots.

Perform any multiplication or division, from left to right.

to get the result:

4. Simplify square root

Simplify 3025 by finding its prime factors.

                    3025

                   /         \

                 /             \

             5                  605

              /                    \

            /                        \

          5                          "121"

           /                            \

         /                                \

        11                                11

The prime factorization of 3025 is 5² • 11²

Write the prime factors.

= √5 • 5 • 11 • 11

Group the prime factors into pairs and rewrite in exponent form.

√5 • 5 • 11 • 11 =

Use rule = x to simplify futher.

= 5 • 11

5 • 11 = 55

5. Solve the equation for x

x =

The ± means two answers are possible:

x = 4

or

x = - 7

15

step-by-step explanation:

we are given the following expression and we are to solve it and find the product:

-13 × (-5)

solving the given expression in the standard order of solving a mathematical expression, beginning with the opening of brackets and then multiplying the terms and changing their signs.

-3 × -5 = 15 (answer is positive because when negative is multiplied with negative, it gives a positive answer)

hello,

b) 62.47% of the students are between 14 and 18 years old.

step-by-step explanation:

mean = 15 and standard deviation = 2

student between 14 to 18

formula used z-score

for age 14 , z score

using z-table , p(z> -0.5)=0.3085

for age 18 , z score

using z-table , p(z< 1.5)=0.9332

p(-0.5< z< 1.5)=0.9332-0.3085 = 0.6247

thus, 62.47% of the students are between 14 and 18 years old.

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