Question

If p+q=10 and pq=21 then find the value of 3(p^2+q^2)

Answer 1

Answer:

174

Step-by-step explanation:

Given,

p + q = 10 and pq = 21

3(p² + q²) , we can split this as,

3[(p + q)²- 2pq], if we substitute the given values then,

= 3[(10)²- 2×21]

= 3[100 - 42]

= 3[58]

= 174

Therefore 174 is the answer.

Hope its helpful!!!

Answer 2

Answer:

Step-by-step explanation:we have a formula: x^2-(a+b)x+ab=0

here a and b are the roots of the equation

assume here a and b are p and q in your problem

by substituting in the above equation;

then,

x^2-10x+21=0;

x^2-7x-3x+21=0;

x(x-7)-3(x-7)=0;

(x-7)(x-3)=0;

x-7=0   ;       x-3=0 ;

x=7      ;        x=3 ;

hence the values of p and q are 3 and 7 respectively

now;

value of 3(p^2+q^2) = 3(3^2+7^2)

                                = 3(9+49)

                                = 3(58)

                                = 174