Question

The area of the triangle above is 21. What is the value of x?

Answer 1

The answer is 6
I got it wrong on the test because I picked 7 automatically my mind thought of 7x3 but it's the wrong math

Answer 2

Answer:

$x=6$

Step-by-step explanation:

We have been given an image of a triangle. We have been given that area of the triangle is 21. We are asked to find the value of x.

We will use area of triangle formula to solve for x.

$A=\frac{1}{2}\times {Base* Height}$

Upon substituting our given values we will get,

$21=\frac{1}{2}\times ({(x+1)*x})$

$21*2=\frac{1}{2}*2\times ({(x+1)*x})$

$42=x^2+x$

$x^2+7x-6x-42=0$

$x(x+7)-6(x+7)=0$

$(x+7)(x-6)=0$

$(x+7)=0\text{ or }(x-6)=0$

$x=-7\text{ or }x=6$

Since length can not be negative, therefore, the value of x is 6.