6(7)^2+4(7)+8=y
6(49)+28+8=y
294+28+8=y
330=y
Rational number, in arithmetic, a number that can be represented as the quotient p/q of two integers such that q ≠ 0. In addition to all the fractions, the set of rational numbers includes all the integers, each of which can be written as a quotient with the integer as the numerator and 1 as the denominator.
The value of X would be 3.6 because if you divide the 4 by 2 to get the half triangle you now know the base and height for the triangle. Now you have to use tangent -1 to figure out the bottom right angle which is 56.3 degrees. Once you have the angle you can use Sin to figure out the missing side.
Assuming yo mean
k²-4k-21
factor by doing
what 2 numbers multipily to get -21 and add to get -4?
-7 and 3
(k-7)(k+3) is factored