Dimitri is solving the equation x2 – 10x = 21. which value must be added to both sides of the equation to make the left side a perfect-square trinomial?
0
4
25
100

option-C

25

Step-by-step explanation:

we are given

Since, we have to complete square of left side term

so, we can use formula

so, we can split middle terms in 2ab form

we can write as

now, we can compare this with formula and find 'a' and 'b'

we get

a=x and b=5

so, b^2 term is missing to complete square

so, we should add both sides by b^2 or 5^2 because b=5

we get

So, we will add 5^2 or 25

step-by-step explanation:

1. 180°. the sum of the interior angles of a triangle is 180°, for the equilateral triangle that it has three equals side is 60°+60°+60°=180°.

2. 60°. each interior angle of a equilateral triangle is 60°

3. 120°. the measure of ∠m is 120°, the sum of the angles ∠m and ∠n is equal to 180°. so, in order to find the measure of ∠m, we have ∠m+∠n=180° > ∠m=180°-∠n > ∠m=180°-60°=120°.

4. 360°. the sum of the exterior angles of an equilateral triangle is ∠m+∠r+∠x=120°+120°+120°=360°. the exterior angles of any triangle always add 360°.